odd mobo/cpu problem

hey guys,
yesterday i was just cleaning my computer (it had picked up some dust) and when i booted the bloody thing wouldn't POST. the monitor said the cable was connected but there was so signal (and then went to power save mode), the fans would all turn on and the lights would go on, the dvd drive and all would be whirring and what not, but the thing wouldn't go beyond that. once or twice i was able to go all the way to window, the last time being last night when i left the machine on for a few hours while i was out, and when i came back it wouldn't awake from sleep mode. now it just won't POST.
any suggestions? i'll go home and check the cpu, but thought i'd ask around before that.
any help would be great...

How did you clean your computer? Wet rag? https://www.sharkyforums.com/images/.../2005/06/5.gif
Try removing all cards from the PC, use a can o'air on em and put em back in (make sure they are all the way in).

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Athlon XP 1900+
ABIT KR7A-RAID
512MB PC2100 DDR
2x60gig Maxtor ATA100 HD
LG GCE-8160B 16x-10x-40x
Pioneer DVD-113
VisionTek GeForce3
SBLive Value
3COM 10/100 ethernet

tried that.... http://dev.www.sharkyforums.forums.relay.cool/ lots of times... nothing seems to work... i guess i'll just send the thing back. :P