random BSOD's

I have been getting a BSOD lately. Almost every day when i use my pc, it crashes 1-2 times. BSOD's happens when i'm using basic programs like firefox, mIRC, ABC and Winamp at the same time.

specs:
AMD Athlon XP 1900+@1200 MHz (it's underclocked)
memory: 2x256 MB
Abit KT7A
Elsa gladiac 511
LG GSA-4163B CD/DVD burner
Creative Sound Blaster PCI 128

OS: Windows XP SP2

Please, help me with this problem.

Hi,

The culprit may be faulty ram because your windows crashes with bugcheck code 1A and two minidumps are crashed with IRQL x'ff'. They are the symptom of faulty memory.

Suggestion
1. Run memtest. If memtest does not find any errror, de-install ZoneAlarm.
2. If it still crashes, re-install windows


Debug report
Mini112605-01.dmp BugCheck 1000008E, {c0000005, bf82e0f5, b9bc7aec, 0}
Owning Process 82053450 Image: ctfmon.exe
Probably caused by : win32k.sys ( win32k!GetRealOwner+12 )

Mini112705-01.dmp BugCheck 100000D1, {0, ff, 0, 0}
Owning Process 80558e80 Image: Idle
Probably caused by : amdk7.sys ( amdk7!AcpiC2Idle+33 )

Mini112905-01.dmp BugCheck 1A, {3451, c02e6abc, 81aa2940, 0}
Owning Process 823ca830 Image: System
Probably caused by : memory_corruption ( nt!MmInPageKernelStack+119 )

Mini120505-01.dmp BugCheck 100000D1, {34343434, ff, 0, 34343434}
Owning Process 817e4b28 Image: vsmon.exe
Probably caused by : ntoskrnl.exe ( nt!KiSwapThread+46 )

Mini120605-01.dmp BugCheck 19, {20, 8177d000, 8177dbf8, 7f7f7f80}
Owning Process 818fe388 Image: abc.exe
Probably caused by : ntoskrnl.exe ( nt!ExFreePoolWithTag+2be )