I built my computer yesterday and initially I could get no response out of it. The motherboard lit up but nothing happened. So I rebuilt it and realized I had failed to use the copper pieces that seperated it from the motherboard and thus grounded it out. Oops. I fixed it and the computer worked absolutely fine. Installed windows, played games, restarted it a ton of times. I shut it down this morning and when I got home from work it won't start up and looks just like it did when it was grounding out. nobody has touched it since this morning, I don't have any idea what could be causing this. Any ideas?

I noticed that one of my screws fell out somehow that was attaching my motherboard. I kind of feel like that is reasonable. I have no 9th screw now =/

You should be able to get standoffs/screws from a local computer store. cyberguys.com sells kits with these and other screws, good to have around

Vibrations still could be causing parts to come loose... I'd try reseating the RAM, and any cards, drives before jumping to the mobo posts... especially if you did actually put the copper posts in and had it working for a while. Any beeps on startup? Is your system speaker hooked up?

^I never had vibration make RAM or any screws come off. It is highly unlikely that vibration is a cause. It could also be that some thing shorted out (like when the screw fell,or some thing like that or ESD.). It could also be a BAD PSU.

Very true... but vibration can very easily partially unseat a card, or partially unseat a drive connector. Some (most) BIOS are very unhappy w/ that an refuse to POST.

I'm hoping for waywardryan's sake that it was not a short (from when he was not running it properly grounded). It could very easily be a BAD PSU, as you say (which is a real pain to isolate w/o some spare parts handy).