There is no good reason for a hard drive to go from 80% free to no free space overnight, so I would suspect that (to paraphrase the Bard)
something is rotten in Denmark.
Unfortunately, the MS Answers forums implementation does not prompt for any system information when a new question is asked, so we know absolutely nothing about your system.
Not knowing fundamental information about a problem prolongs the frustration and agony of resolving these issues but that is the way they choose to run things here.
Thank you MS Answers owners, for continuing to make the resolution of simple problems as frustrating and time consuming as possible.
What is your system make and model?
What is your XP Version and Service Pack?
Describe your current antivirus and anti malware situation: Microsoft Security Essentials (MSE), McAfee, Symantec, Norton, Spybot, AVG, Avira!, Panda, Trend Micro, CA, Defender, ZoneAlarm, PC Tools, Comodo, etc.
There is some malicious software that will generate enough temporary files on your system to render it inoperable so take measures to be sure that is not the problem:
No matter what else you are using for malicious software protection, do this:
Download, install, update and do a quick scan with these free malware detection programs (not at the same time) and remove any threats:
Malwarebytes (MBAM): http://www.malwarebytes.org/products/malwarebytes_free
SUPERAntiSpyware: (SAS): http://www.superantispyware.com/
SAS will probably report a bunch of tracking cookies and you can just let it delete them.
They can be uninstalled later if desired.
When the scans run clean, reboot and then troubleshoot any remaining issues.
If you want good help that does not involve guessing or trying things, do this:
From your desktop, double click My Computer, right click the drive or volume on which XP is installed and choose Properties.
Reply back exactly what you see without paraphrasing the:
Type:
File system:
Used space:
Free space:
The Windows defrag reports lists files that cannot be defragmented - is that what you are talking about and what are the names of the files?
If you want someone to look at your defrag report, you can save the report to your desktop as a text file (something like VolumeC.txt) and then copy/paste the contents back here.
If you are running low on disk space the Windows defragmenter may have difficulty defragmenting your hard disk. XP needs 15% of the total hard disk capacity to run properly (you would get an informative message if you don't have enough room).
The XP defragmenter is a slimmed down version of the popular tool from Condusiv Technologies called "Diskeeper". It does a pretty good job most of the time, but there are some other tools (many of them free) that folks like better.
It makes sense that the XP defragmenter cannot defrag files that are in use (like the registry files, Event logs, hiberfil.sys, pagefile.sys, etc), so they may show up as fragmented files in the defrag report. These files must be defragmented before XP loads
up all the way and starts to use those files. Microsoft has a tool called "PageDefrag" to help you with some of those files.
PageDefrag will add an entry to the registry to run the page defragmenter on the next reboot. The registry entry is automatically removed after the system reboots. Then these files and other system files will be defragmented on the next reboot, but you still
may not end up with zero fragmented files.
Get PageDefrag and other good tools, videos and commentary by Mark Russinovich, the master of Windows troubleshooting here:
http://technet.microsoft.com/en-us/sysinternals/bb545021
On a healthy system it is certainly possible to have zero fragmented files (according to the XP report) by using the built in defragmenter and PageDefrag. Defragmenting your HDD does not mean that you will suddenly see more free space on your HDD though (that
is not what it is for), so don't let your expectations exceed reality when you get to zero defragmented files and still have no more free space.
Here is an example of such a report (VolumeC.txt) showing zero fragmented files I ran on my system:
Defrag Results
Volume (C:)
Volume size = 932 GB
Cluster size = 4 KB
Used space = 68.00 GB
Free space = 864 GB
Percent free space = 92 %
Volume fragmentation
Total fragmentation = 0 %
File fragmentation = 0 %
Free space fragmentation = 0 %
File fragmentation
Total files = 144,366
Average file size = 677 KB
Total fragmented files = 0
Total excess fragments = 0
Average fragments per file = 0
Pagefile fragmentation
Pagefile size = 5.22 GB
Total fragments = 0
Folder fragmentation
Total folders = 19,104
Fragmented folders = 0
Excess folder fragments = 0
Master File Table (MFT) fragmentation
Total MFT size = 294 MB
MFT record count = 165,343
Percent MFT in use = 54 %
Total MFT fragments = 0
Fragments File Size Files that cannot be defragmented
None
There are many free third party defragmenters you can download from the Internet. Some folks like the other tools better than the built in XP defragmenter, although you can see from the report above, the XP defragmenter is certainly capable of a result of
zero fragmented files but sometimes you have to run it many times or do some unnatural things to get to that point.
Here are some examples (in no particular order) of popular third party tools that you can investigate and you can do some Google searches for others:
Some people like the Piriform suite of products and their Defraggler application which you can get here:
http://www.piriform.com/
Some people like the Auslogics suite of products and their defragmenter application which you can get from here:
http://www.auslogics.com/en/
Some people like the PerfectDisk suite of products and their defragmenter application which you can get from here:
http://www.raxco.com/
Diskeeper (not free anymore)
http://www.condusiv.com/products/diskeeper/