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I'm having the usual classpnp.sys problems after a motherboard replacement (due to the Intel Sandy Bridge issue with failing SATA ports). Basically the thing goes into a loop where none of the F8 menu options results in a boot.

The strange thing is that it does occasionally boot. I mean very occasionally, maybe 1 in 30 tries. But recently it's literally not even been that reliable.

I tried reinstalling from the Windows 7 CD, but now running that causes a reboot too.

The motherboard is a Gigabyte P67A-UD4 B3 (which is the 3rd rev of the board, I originally had a P67A-UD4.

My only guess is that I should make an Ubuntu disk and see if I can replace the classpnp.sys file from another Windows 7 disk.

I'm trying desperately not to have to reinstall the whole OS, because I've got a lot of stuff installed.

Any idea what classpnp.sys actually does? Or if there's another way to fix the boot?

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Ok, so it booted once again (after about 50 or so retries), I tried a repair install from the win7 disk and got to the "reboot" part and its back to its old shenanigans. – Phil Carlisle May 14 '11 at 10:56
Ok, so I made an Ubuntu disk and that runs just fine. So its definitely something with the boot process in win7. The fact that it does occasionally work is confusing me. – Phil Carlisle May 14 '11 at 12:06

Use sysprep.

run>sysprep>enter>select Audit mode+tick generalize>select shutdown>select OK>power system back on>install driver.

If it wont boot, boot off of a W7 DVD, go into the Recovery , at the 1st screen press 'shift+F10', in the CMD windows that follows, navigate to "C:\WINDOWS\System32\oobe\" and type "msoobe.exe" [Enter].

A window should pop up, follow the steps,reboot your PC. You should now be able to run Sysprep which is s systems preparation tool to migrate installations across hardware.


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Welcome to Super User.  I’m impressed; it’s not every new user who posts eight answers in his first 28 hours of membership.  Since you clearly have the time to invest in making Super User a great repository of useful, reliable information, would you please be so kind as to edit your answer to make it clearer and more precise?  For example, are you suggesting that the user try to reboot his machine another 49 times, and, when it succeeds (on the 50th attempt), he should follow your instructions?  Or should he boot off a CD?  … (Cont’d) – G-Man Jun 23 '15 at 0:47
(Cont’d) …  Next, when I do “Run” → sysprep, a Windows Explorer window opens, pointing to C:\Windows\System32\sysprep.  That folder contains a sysprep.exe.  Are you suggesting that the user double-click that program?  What is “sysprep”?  Can you describe it in a sentence or two, and provide a link for reference?  Can you explain the function/purpose of the action sequence you listed?  What does “Audit mode” have to do with this question? – G-Man Jun 23 '15 at 0:48
G-man thank you for the guidance, it is appreciated although I do feel if someone it at the point in their quest for knowledge / experience that they are migrating OS install's between hardware configs, they can also put one and one together with regards to clicking syspre.exe . The rest can also be Googled, Microsoft have extensive articles that explain simply, and go further into great detail if the knowledge is required. – OxygenIT Jun 23 '15 at 8:24

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