days of trying everything! issues with C being full... tried all suggestions dozens of times!

Question

Windows 11

will try to put nutshell version... a few days ago my computer started dragging... errors popping up that C is full... or file to big to sync to onedrive, etc.
Also some explore.exe application box pop up with 'the memory cannot be read' and box with 'free up space to continue' Choose sites to clear... and some others too...other messages like not enough resources, etc.
Computer locks up and i have to either to restart and sometimes just have to manually cut off to unlock and get going again...
my computer guru (has been doing this for decades) is puzzled... said he's never seen anything like it... been tinkering with my computer for days...

we've done all the usual recommended things to clean space dozens of times... and i have a longgggg thread from chatgpt with suggestions to questions i've asked related to this and scoured youtube videos too, pretty much tried them all...
talked to somewhere yesterday my fellow connected me to to see about moving some stuff to a different partition (i am completely computer illiterate about such!) and long story short there, he looked around and said whatever my tech asked me to ask them couldn't be done, but for (spouted out 3 levels of fees from about $150-$399 to have their VIP service look and see if they could help... that was worrisome as there was no guarantee for such money!

yesterday, i spent hours moving many files and folders over to external hard drive them deleted from C, then it showed 16.9g free just before my head exploded and went to bed last night, thinking i could get up and back to work this morn after freeing up those gs.
No such luck!
This morning it showed 1 g free. At one point showed 0 free.
It's like everytime we do something it undoes it and goes right back like it was. Called MS support but they won't talk to me w/out paying them $300 and just can't do that right now...

Do I have a gremlin in this thing? My nightly iDrive backups can't backup because of this issue... could there be some connection to that? I realized Monday I hadn't been getting my morning backup report from them so I called their (great) tech support and he tweaked some things and did a "backup now" but when i got home later, the backup had failed due to this space issue! Also, a week or 2 ago, when I called them about this and he logged in and looked around, idrive wasn't even installed on my computer! It WAS there... so we have no idea how that uninstalled itself either so he did reinstall that last week.
I need to work! Just keep getting these same messages, computer locks up and have to shut down and trying to do one thing at the time to prevent this 'not enough resources" etc. messages.

The only thing my tech knows to do is wipe clean and reload everything. I'm trying last efforts to find help or culprit and a fix before he has to do all that. This started Monday and have been able to do little to no work all week! help please!!

Sure would appreciate any help...

#windows11home

Answer 1

Hi Wendy,

I understand how exhausting this is, especially when you free space, reboot, and it immediately disappears again. The Q&A Assist has given a very detailed list of what you can do, so I’ll go deeper on what is possibly happening and maybe try to stop it.

From your description, this is not normal low‑disk behavior and simple cleanup might not be able to fix. There’s likely something constantly writing data back to C:, that’s why you see 15–20 GB free at night and almost nothing again after restart.

The most likely cause is a sync or backup service stuck in a loop (OneDrive, iDrive), runaway system crash dumps, or uncontrolled restore-point growth caused by repeated system freezes. Let’s try the following in order to see if anything change:

1 - Temporarily stop sync/backup completely

• Exit OneDrive fully > stop, turn off, sign out.
• Do the same with iDrive > Restart the PC.
• Check C: space and wait a few minutes
• If space stops shrinking, you've found the cause.

2 - If space still drops, limit System Restore usage

• Press Win + R > type sysdm.cpl > press Enter > open System Protection
• Select drive C: > click Configure > Set Max Usage to 3–5%
• Click Delete to remove existing restore points.

3 - Isolating the cause of issue with Clean Boot

• Follow this guide on How to perform a clean boot in Windows - Microsoft Support 
• Find msconfig > disable all non-Microsoft startup items/services > restart PC.

If the problem is gone, it's likely that one of your downloaded apps was the cause. You may need to manually enable them half-by-half to identify the offender, then consider removing or disabling it. 

Disclaimer: A "clean boot" starts Windows with a minimal set of drivers and startup programs. It helps to determine whether a background service is interfering with your game or program and to isolate the cause of a problem. They might look complicated at first glance but can help you get back on track. To avoid any trouble, please follow them in order and step-by-step.  

A full wipe should be the last resort. If you reinstall Windows and restore the same backup or sync configuration, the problem will return immediately. Let me know the result of the testing above, and we will progress from that.

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Answer 2

The behavior described matches a system drive that is critically full and immediately refills due to system/temp data, cloud sync, or other background processes. Before a full wipe, use the built‑in Windows tools in this order to both free space and stop it filling back up.

1. Check actual free space and what is using it

• Press Windows key + E to open File Explorer.
• Select This PC and look at Local Disk (C:) to confirm free space.
• Still in This PC, right‑click Local Disk (C:) > Properties > General tab > Disk Cleanup (if available) and note how much space is shown as temporary/system files.

2. Turn on and configure Storage Sense Storage Sense can automatically clear temp files, Recycle Bin, and previous update files that may be refilling the drive.

• Select Start > Settings > System > Storage.
• Turn Storage Sense On.
• Select Storage Sense and configure it to:
  • Run Every day.
  • Delete Temporary files.
  • Delete files in Recycle Bin and Downloads after a short period (for example, 1–14 days) if acceptable.

This helps prevent the drive from immediately filling back up.

3. Use Cleanup recommendations (Windows 11) This gives a guided list of large/unused files and system files that can be safely removed.

• Go to Start > Settings > System > Storage > Cleanup recommendations.
• Review each category:
  • Temporary files
  • Large or unused files
  • Files synced to the cloud
  • Unused apps
• Select items that are safe to remove and then select Clean up for each section.

Note: If Windows was recently upgraded, Previous Windows installation (Windows.old) may appear here; deleting it can free many GB but removes the option to roll back to the previous version.

4. Fix Low Disk Space errors quickly If C: is repeatedly dropping to 0–1 GB, follow this focused sequence:

1. Confirm space:

• Press Windows key + E.
• Select This PC and confirm C: free space.

2. Clear Microsoft Store cache (can grow very large and refill Temp):

• Press Windows key + R.
• Type wsreset.exe and select OK.
• Wait for the blank Command Prompt to close and Microsoft Store to open.

3. Restart the PC:

• Select Start > Power > Restart.

4. Ensure Storage Sense is enabled as in step 2.

5. Move personal data off C: and change where new content is saved Since a lot of data was already moved to an external drive, also change default save locations so C: does not keep filling.

• Select Start > Settings > System > Storage > Advanced storage settings > Where new content is saved.
• For each content type (Documents, Music, Pictures, Videos, etc.), choose another internal drive if available. If only an external drive exists, ensure it is always connected when saving there.

6. Use OneDrive Files On‑Demand instead of full local copies If OneDrive sync is complaining about large files and filling C:, enable Files On‑Demand so files stay in the cloud and only download when opened.

• Turn on OneDrive Files On‑Demand (see Save disk space with OneDrive Files On-Demand for Windows from the reference article).
• After enabling, right‑click large OneDrive folders/files in File Explorer and choose to keep them online-only so they no longer consume full local space.

7. Check for malware or runaway apps consuming space Because space keeps disappearing, a process could be generating logs or temp data.

• Run a full scan with Windows Security (built‑in antivirus).
• If already done, run it again after enabling Storage Sense and clearing Store cache to ensure nothing new is present.

8. If Temp folder is refilling rapidly (Low Disk Space + Store/Update issues) If Low Disk Space errors mention Temp or appear after Store/Update operations, follow this sequence:

1. Reset Microsoft Store apps troubleshooter:
   • Start > Settings > System > Troubleshoot > Other troubleshooters.
   • Next to Windows Store Apps, select Run.
2. Clear Store cache again:
   • Windows key + R > type wsreset.exe > OK.
3. Run Windows Update troubleshooter:
   • Start > Settings > System > Troubleshoot > Other troubleshooters.
   • Next to Windows Update, select Run.
4. Restart the PC and monitor free space in This PC.

9. Use external storage for Windows updates (if updates are failing) If Windows updates are failing because of low space, use an external drive or USB to complete them instead of consuming more C: space.

• Follow Use external storage to install the latest Windows update in the reference article to offload update files to external storage.

10. When to consider reset/reinstall If, after:

• Enabling Storage Sense,
• Running Cleanup recommendations,
• Clearing Store cache,
• Running troubleshooters,
• Moving personal data and changing default save locations,

C: still drops back to nearly 0 GB within minutes or hours, the system may be severely misconfigured or corrupted. At that point, a Reset this PC with Keep my files (not full wipe) is the next built‑in option to repair Windows while preserving personal data. This requires enough free space to start, so perform all cleanup steps first.

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References:

• Free up drive space in Windows
• Fix low disk space errors quickly in Windows