my continued nitemare with that generic P4-PC

its an ECS 865pe-A v2 mb. replaced memory b4 X'mas. still give me blue screen 0x00000050, 0x00000024 errors. MS error feedback suggests that has something to do with drivers/anti-virus.
I think its mainboard. updated BIOS to the 2005 version. no luck. the client said it crashed oftern in skype.
for me, it would intermittenly crash doing Malware scan, or MS essential security scan.
changed memory twice, still no luck.
use Hiren 10.1 CD to test it, it passed the memory (except one - troubleshooter?), mb, hdd, cpu.
I have since disconnected one cdrom to save power for the 300W P/S.