i have a 2003 hp running xp sp2 well i decided to vac. the dust out of it since its been a while. also it was getting real hot. the cpu fan just barely working. well when i put it back together and hit the on button it seemed to start then shut itself right back off. thats it nothing on then off?? can anyone help?? t-ony@sbcglobal.net

So the PC doesn't start at all? Several questions:
1. Do you see the small LED on the motherboard? It lights red or green?
2. When you put the hand on the PSU fan grill do you notice the air flow coming out of PSU?
3. Do you hear any beeps / warnings from mobo?
4. As I understood from your post, you don't seem to see the BIOS, right? So you don't see the POST screen displayed too, yes?

thanks for reply: as far as red or green lights i dont see anything, i really dont have time to see anything as it shuts off right after the cpu fan kicks on. on one occasion i took the ram stick out and it started to give intermittent beeps. but no bios what so ever?? thanks