Irregular crashing

[Skizzitt18]

Hello!
I've recently (as in within the past 4 days) been experiencing crashing on windows xp.
It crashes while running Firefox, while playing games, trying to set a desktop background, and even when sitting with no programs running!

I have installed a new back-up hard-drive, (Western Digital 750g) but that was almost over a week ago now.
Haven't recently installed a any new software.
Only thing I have added is a new case-siding fan, which was about 4 days ago.

And I say irregular because there is no set-time frame for the Blue-Screen, it could be anywhere from 10minutes to indefinite.

Any suggestions or help guys?

Thanks in advance.

 

[treefrog07]

Post your system specs: makes and models. Have you made any changes to the BIOS settings? If not, you may have a peice of hardware that is failing

 

[Skizzitt18]

MoBo: Asus P5KPL-AM SE
Chipset: Quad Q6700
Video: Geforce 9500GT
Sound: Onboard
RAM: 800Mhz DDR2 1gig sticks x2

And no, I have made no changes to BIOS settings.

Small update as well.
-Unplugged the new backup drive and the crashes are still coming, but
the crashes are not coming within an hour now, they are taking quite some time.