BSOD again - Memory management, Driver irql ..., Pfn list corrupt!

Hello again,


Please help me to solve my BSOD.
I have it for a few months. I upgraded from Win XP to Win7, changed the antivirus/firewall system to Comodo, updated drivers and did other things. After changing 1 module of RAM 512 MB, some crashes disappeared, only bsod at boot time remained. I deleted existing settings at Driver Verifier, and after that (I suppose that was the reason) the crashes disappeared. Now I don't have BSOD for 2/3 weeks.
But now BSOD came again in the last 3 days. The bluescreen view showed that most of the time ntoskrnl.exe is the problem.
It would be good to know, that is it a driver failure (if so, which one), or BIOS update (but I couldn't find a proper new one) or a Win7 reinstall?
Thank you very much

Is it possible that the problem is the paging file? By default it was handled by Win7 and the size was 1 GB (like the amount of RAM). I modified it manually between 1,5 and 3 GB. Any ideas?
Thanks

Check your memory.

Download Memtest86+ from this location here. Burn the ISO to a CD and boot the computer from the CD from a cold boot after leaving it off for an hour or more.
Ideally let it run for at least 7 passes / 6-8 hours. If errors appear before that you can stop that particular test. Any time Memtest86+ reports errors, it can be either bad RAM or a bad Mobo slot. Perform the test RAM sticks individually as well as all possible combinations. When you find a good one then test it in all slots. Post back with the results.
See this Guide to using Memtest 86+

Then check your hard disk(s), especially your system disk.
Open an elevated command prompt and type
chkdsk C: /R
hit enter
answer in the affirmative "Y" when prompted
reboot your computer
let it finish all five stages and check the results in event viewer.
You may also want to go one step further and obtain vendor specific proprietary hard disk analysis software from your hard drive manufacturer. Most top tier vendors provide something of the sort, a list of some can be found here Hard Drive Diagnostics Tools and Utilities (Storage) - TACKtech Corp.

Hello,

I made memtest run last night until 6 passes and found no errors.
RAM should not be the problem (I hope), I changed 1 module about 2 months ago, the other seems to be OK by this testing. Check disk and system file checking was already done. One of them made some repair but no change in the whole.
I suspect some of the drivers, because deleted settings in Driver Verifier and after that the crashes disappeared (for a while . Or Comodo Firewall (sandbox especially) could be the cause? I think the next one will be to uninstall that.