Windows XP Pro SP3 - Crash problem

I have been having issues with my operating system crashing on a regular basis. It does it mostly when explorer is open and I am trying to install a few things. I know installing takes a little extra resources, but I am not do that much were the computer should stop responding. When it crashes, I can hit ctrl+alt+del and see my task manager, I can move my mouse, but I can't click my mouse on anything. The task manager updates and runs like normal.

I just installed WinXP Pro SP3 on a fresh install so there shouldn't be any errors in the OS yet. I can only guess that my older computer is having troubles. I cannot find the BIOS to reflash it, nor do I know if that would help. Also would overclocking my processor help or most likely hurt?

Any ideas welcome.