Cannot power up... HELP!

[wh00kah]

This is really starting to confuse me...

Here is some background to preface this problem.
Duron 700 with Coolermaster Heatsink/Fan
Asus A7V Rev. 1.02
384 MB PC-133 SDRAM (Micron)
300 Watt MPT-301 ATX Power Supply
GeForce 2 MX w/ 32 MB SDRAM (Guillemot Hercules)
Western Digital Caviar 19 Gig HDD IDE
Pioneer 515 IDE DVD-ROM drive
Phillips 4x2x20 IDE cdr/w
SP (Super Power) Mid-tower case
Generic Case fan

I just bought the components and put a system together myself (possible mistake).
It worked great for a few weeks. I then put the DVD-ROM drive noted above
in and now the damn thing won't power up. The mobo power-on indicator LED comess on, but
the fans on the power supply, CPU, and on the case do not power up when I plug
the power supply in. They just twitch a little and then stop. I can't turn on the computer
for any reason. Weird. I tried disconnecting components one by one starting with the DVD-ROM drive. No go. I'm worried I might have fried something with that damn flaky dvd-rom drive.

But here's the strange thing. SOMETIMES, when I put the computer on it's side with the side case cover off, and plug it in, the fans come on for a bit, stop, and then I CAN power it on. It loads up and boots up Windows 2k perfectly. I then tried to turn it upright and put the case on for airflow... AAARRGHGHHHH! The thing completely shuts off.
I unplug the power supply plug and then replug... no go. The same "fan twitch" as before.
Now turning it on its side doesn't even work. I just recently replaced the old power supply with the MPT-301 noted above, thinking that was the problem. Nope, neither Power supply works.

Sorry the post is soooo long, but I wanted to be as thorough as possible.
PLEASE HELP ME! Thanks in advance.

wh00kah

 

[AKA]

Sounds like maybe a short. Make sure your motherboard is mounted properly. Reseat all components also.. video, memory and cpu.

Then you might try another power supply.

 

[wh00kah]

A.K.A, you've saved my computer from being thrown out the window in disgust.

I tried reseating the mobo... guess what falls out through the bottom? The infamous
stray screw bit behind the mobo smiling at me like a gremlin. That little screw lodged inbetween the case brackets and the mobo, scraping up against traces on the mobo no doubt. That's what caused the problem.

Thanks again, A.K.A. You've got me liking computers again

Now, to get Win2K and Linux Mandrake to like each other

------
wh00kah
Now humbled by his own stupid carelessness

 

[AKA]

Im glad you got it working.