|Is this during Power On Self Test (POST), when you computer first powers on, or after you see the Windows logo and start to boot into Windows. |
It sounds like it is happening during POST which would indicate a serious problem like a bad mother board, bad ram, bad CPU, or bad Graphics Card. If so then try pulling your Graphics Card or RAM out and putting them back in. They may have come lose. If that does not work then it is time to take it into a technician.
If the problem occurs after the Windows Logo then it is a less serious problem and is probably an incompatible driver issue. Try booting into safe mode by holding down the F8 key when booting up the computer. This will load windows with basic drivers.
With out more information we can not pinpoint the issue so we need the WHEN and the WHAT happened before this issue. Did you do an upgrade, did a windows update run or any thing that might have lead to this.