Explerer.exe causes errors!

[phx]

For the last two days , whenever i try to right-click to an file ,
explorer.exe rises an error and closes all the application , restarts
itself.
Before this started 2-3 days ago , i installed sp2, just before started i
installed the final version of ati drivers (for my asus radeon9600xt), ati
drivers caused an error while installing , and i reinstalled them .
Mcaffee had updated itself to an final version.
I am also using the final version of ZoneAlarm.
Any idea what the cause maybe?
P4-2400HT
512mb ram
Asus p4p800 board

 

[phx]

The error Explorer.exe rises is :
"The instruction at 0x350415b referenced memory at 0x00000000 . The memory
can not be "written" . Ok to terminate , cancel to debug"

Thank you for any help.