Very randomly my MONITOR will go from normal to being COMPLETELY covered in jagged colored lines. The lines always go left to right at an upward angle. Sometimes they are randomly colored, sometimes just grey, black, and white. I'll restart my PC and it will be fine.

When it happens I can't see ANYTHING on my monitor but the lines, and really they are more like bars instead of lines.

I haven't noticed anything that would be causing it to happen, like using a certain program or website. Its completely random ><

Could someone give me an idea of what the problem could be?

Edit: thought it might be helpful if i gave alittle info about my computer.
It's a store bought Emachine, W3107, everything is factory besides the RAM. Video card is nVidia GeForce 6100. I have XP as the OS, not sure if i need to give anything else.

Thank you for help.Remove a side panel.
Re-boot and check to see all fans are operational.
If so remove all power sources and ground yourself to the case.
Remove and re-seat the VID card.
Connect all power and re-boot and see if this changes anything...

P.S. Did you add this vid card ? ?
eMachines are notorious for weak PSU's...