The aswMon2 function on the stack is just the filter passthrough routine, so I wouldn't say the problem has anything to do with it (even though the only way to be really sure is to uninstall avast and see if the problem stops happening).
What I'd suggest is try to run a memory test on your machine.
If you have a CD burner, the best way is to download, burn and boot from the MemTest86+ CD
http://www.memtest.org (or I think there's a version that filts on a floppy as well).
It's free and works extremely well.
Let it run overnight and see if it reports any problems.
Thanks
Vlk