problem with my pc

[anbhal]

I have an IBM ThinkCenter (Tower PC, Pentium 4, 3.0GHz, 1GB memory (4x256MB)). When I play a game the computer screen begins to flash every second or two after about one minute of starting the game?

Does anyone have suggestions of what maybe the issue? Thanks for your help.

[Keymaker]

What steps have you took to find the cause?

[anbhal]

Done nothing so far. I have another computer, same model and only difference is softwares (minimal difference), different hard drives and ram (both 4x256MB)