lots of BSOD

hello
I have this rig
AMD ATHLON 64 3000 SOCKET 939 BOX
2/ A-DATA 512 MB DDR 3200 MEMORY
GIGAYBYTE GA-K8NF-9 NFORCE4 SOCKET 939
RADEON HD 3600
THERMALTAKE TT420APD 2-FAN APFC POWER SUPPLY
lately I get BSODS always after windows starts
the error is 0x0000000050 page_falt_in_nonpaged_area
here is the minidump
few things that I tried
checked my memory with memtest and the result is good
ran command chkdsk /r on my hd
what it could be?
tanx

 

Are all your card seated well on the MOBO
Your disk could have bad sector, you say the memory checks out, run a full diagnostics on the disk with the disk manufacture program.

 

last week I took out the mobo because I installed cooling fan on the processor
the pci card can cause it?
I need to know what to check in the mobo because I think its related
to the dismantlement of the mobo

 

Did this happen directly after you installed the fan. Check that all the cables are set tight