Windows 7 boot stalls at classpnp.sys

You are a life saver bro... 

Before trying this solution ( which actually worked for me), i tried many other solutions suggested on different forums, but none worked accept this one.

This is genius.

You deserve a lot of appreciation.

Thanks a lot for help.

Hi,

I would have you create a new thread of your own to avoid confusion and get a better exposure.

Refer the link-

http://answers.microsoft.com/en-us

Do get back to us for any issues pertaining to Windows in the future. We will be happy to help.

This problem seems pretty widespread and I read lots of threads to try and fix this and was not looking forward to rebuilding PC but I got lucky. Suggest you try this for yourselves as it worked for me.

I originally only posted this on one thread but have had feedback that it has worked for someone else so posting this more widely now.

·         Reboot in Safe Mode with Command Prompt

·         When the boot script freezes at "CLASSPNP.SYS" line hit <ctrl><break>

·         When I tried this it killed the frozen command line session and then Windows went on to reboot in safe mode

·         I then restarted in normal mode and hey presto no more problems

·         Not yet anyway

What a surprise that an old MSDOS keyboard command seems to be able, at least in my and one other case, to fix what appears to be a significant Windows problem for so many...makes you think.

Hope this saves a few people from having to do major reinstall work or hardware fixes.

Hi Andrew, 

Fortunately, I found that your suggestion and step given were very useful. I also have the same problem with Windows startup, where it suddenly stop booting at Classpnp.sys. After 2 weeks I tried to find out what actually happen to my PC (with 2 separated hdds).

My problem started when I installed a game into my 2nd hdd. After restarted my PC, it suddenly stopped at Windows logo. I've tried booting in safe mood and as experienced by others, it stucked at classpnp.sys. I detached my 2nd hdd, and surprisingly, Windows restart normally. So, for me, I assumed there must be some problem with my 2nd hdd (maybe affected from game installation).

What I did was, I changed the booting sequence in system setup (F12 for my Dell). I only selected my 1st hdd to start with. As estimated, it still stuck at classpnp.sys after restarting, however, I hit <ctrl><break> at classpnp.sys line, as you suggested. Surprisingly, my day became so wonderful as Windows started in safe mode normally.

Now, I'm trying to find out what actually disturbed my 2nd hdd with chckdisk and other software. Hopefully my experience could help you guys out there.

I bought a Win7/Ultimate machine a few months ago for the parts and disassembled it after a couple days of testing the components. Today I reassembled the motherboard and original hdd to use it as a testing platform and ran into this same problem only my setup would not get past the classpnp driver load under any circumstances. I finally tried changing the drive configuration bios settings from native/ide to native/ahci and stopped when that made no difference. I did not consider trying native/raid because the machine came with a single drive. While reading this thread and thinking about the info presented here I remembered that the fellow I bought it from told me his reason for selling was because he had trouble setting it up in a raid10 configuration and simply bought a new machine to solve that problem. When I reset the bios drive configuration to native/raid it booted right up. I'm guessing he did the original install in raid mode and that became the "required boot configuration". What I gather from all of this is that the issue is "missing hardware required for bootstrap" and it can be a number of different things. Maybe Microsoft could publish a check list such equipment to help with troubleshooting this vexing problem. I hope this helps in some way.

Unfortunately, I have done all of what you suggest.  This is a laptop, and it has failed to boot immediately after an install with nothing external connected as well as later in the install / configure process.  It does not always refuse to boot.  When it will not boot, System Repair (run from the DVD) has announced that there is a problem and it cannot fix it, although it does not state what the problem is.  Memory test shows memory is OK.  Checkdisk (which runs successfully during system repair) shows the hard drive is OK when run from within Windows (when it boots). At one point I totally wiped the hard drive, reformatted, and installed.  During that process, it refused to boot at least once.

The last time it refused to boot was when I realized it was hotter than usual (but not dangerously hot), so I let it cool a couple minutes.  The next attempt booted OK and it has booted OK ever since.  So far.

Note that Vista x64 ran 100% perfectly for a couple years on this same machine.  Additionally, my copy of Win7 is an upgrade copy so although it does a clean install over Vista (Vista is Ultimate, Win7 is Pro so it will not actually "upgrade") it does not actually reformat the hard drive.  Is that a clue?  Is there something remaining from the Vista install that is confusing things? The next boot after a failed boot offers the repair option.  If I take that, it announces something like "a required device is unavailable".  That sounds like something like the hard drive has gone missing.  But it is reading the hard drive (the boot actually begins, it just stalls).

Like I said in my original post, it is currently booting OK.  I have flashed the BIOS and finished all driver installation.  I am merely worried that I have not in fact fixed it since this is a very common problem, reported by many people over the last year or so.  Some of them were using brand new machines with the factory Windows 7 load.  I am merely wondering if anyone has found the real issue and if there is a permanent fix.

I know everyone is trying to help, but if you look at the many threads reporting this problem (stalling on classpnp.sys) running repair and checkdisk etc. NEVER fixes it.  The threads just die out without a solution. 

BTW, MS needs to look at the code for this web site..... using Firefox, there is no cursor when typing, making it very hard to make corrections.  

Paul