Since it is POSTing and your other drive seems to work, I am guessing it is a HDD issue. Try booting Ubuntu from a CD (
LiveCD ) and if that works that would make it even more likely.
If it does seem to be the problem and you cannot detect any loose connections, and the drive won't work in another computer, the platter might have physically shifted in transport or your computer was bumped during the LAN party.
The best way I know to (cheaply) remedy this is to take your HDD out and put it in the freezer. This contracts the metal and could reseat the platter properly. If you do decide to do this, look up tips online, but you need to seal the drive in a airtight bag with some of those silicon packets that come in shoes, to absorb moisture to avoid condensation ruining your drive.