1. Well, at least it seems you don't have a completely broken PC!
2. Hard disk errors doesn't sound too promising! If you've not got one, take a back-up while you can! Check your disk for errors:
http://windowshelp.microsoft.com/Windows/en-us/help/bc1393cf-9f9c-79c7-0f91-9337c2c41f811033.mspx
3.If you can boot up in Safe Mode, have a look at Device Manager for errors. Start re-adding your hardware one at a time and rebooting to see if something here is creating the problem.
4. Were you doing anything, adding software etc, which possibly caused the problem? Do you have a system restore point prior to this?
5 SYNTAX ERROR :-)
Salamat
2 x PC, 2 x Macs......both have their good points
Windows on a Mac = ideal!