Welcome to CF!
How long after selecting a boot up option does it restart?
Are you gettnig a lot of noise from the Harddrive then reboot?
Do you get any beeps when first powering on? I'm assuming just a single beep...
What OS are you using?
Do you have the original Windows Disk?
Could be a couple things, but sounds like a hardware issue
Humans are the only creatures that won't live up to the their potential. Give everything your all. When you die, die on E.
So I ask you, what do you intend to do now?