Strange startup problem

[Kiwibird]

Alright, so I've had Halo PC and CE installed on my computer before and never had any problems with it before. And now, the worst problem that could occur, did. When I try to run Halo CE or Halo PC I double click the icon and nothing happens, at all. What is really strange is when I reinstall it, it works for about 2-3 hours then the same thing happens again. It's getting very irritating having to reinstall it every time I want to test things I've made. Could this be a Virus? That's my only guess.

Also

Video : ATI FireGL V3100
RAM: 1 GB
CPU: Intel Pentium 4 3ghz
OS: Windows XP Pro

I would greatly appreciate any help. Thanks.

[Hunter]

Try doing a system restore point, back about 3 days or so before it started to happen... then it should work.