Laptop shuts down when loading classpnp.sys


Jul 21, 2012
Hello guys! And sorry for a very long post.

My friend ask me to look at his Acer Aspire 4736z laptop that keeps shutting down when windows 7 logo starts to appear . When I tried running in Safe Mode I noticed that it stops at "classpnp.sys" then completely shuts down after 5 seconds.

I tried:

1. Change the sata controller from AHCI to IDE/virse versa. Successfully booted windows once but after several minutes it shuts down again, tried to repeat the process but it never worked again.
2. Repair windows but didn‘t work.
3. Disassembled the laptop, removed some dirt and re-seated some parts specially the memory module. Didn‘t work too.
4. Updated the bios and run some hardware test. No errors found.
5. Run Linuxmint, booted fine but shuts down again.
6. Formatted and install windows, tried so many times sinces it shuts down in the middle of installation. After several times I successfully installed windows BUT SHUTS DOWN AGAIN! Fustrating >_<
7. And lastly, let it stay in bios menu. Guess what? It never shut down! Weird.

I wanna try to use another memory module but i don't have spare one, I don't want him to ask him buy a new one since im not sure if this was the real culprit.

So any suggestion guys? Thanks!


Yea, this is a common issue. The classpnp.sys freeze can be caused by a lot of things. I've had it a few times on my Acer. Manually copying drivers from the windows install CD to the HDD fixed it once. Another time it was a faulty hard drive.

Since it appears that the problem goes beyond the actual windows install, sounds like it could be a faulty hard drive. Linuxmint... are you booting from a livecd, or is it on the same HDD as the windows install?

Do you have any other laptops laying around? Swap out the hard drive and see if it boots.

If it's not the hard drive, you could be looking at southbridge problems. Reflowing it might fix.
Thread starter Similar threads Forum Replies Date
S Laptop Tech Support 1
R Laptop Tech Support 3
kath123k Laptop Tech Support 1
J Laptop Tech Support 2
NightKnight007 Laptop Tech Support 5
rayxmf Laptop Tech Support 3
C Laptop Tech Support 9
Aryamaan08 Laptop Tech Support 4
OsamaHad Laptop Tech Support 1
S Laptop Tech Support 3
Q Laptop Tech Support 3
M Laptop Tech Support 3
D Laptop Tech Support 4
R Laptop Tech Support 1
E Laptop Tech Support 3
S Laptop Tech Support 1
W Laptop Tech Support 2
C Laptop Tech Support 1
W Laptop Tech Support 1
P Laptop Tech Support 19