Open the task manager and "close running tasks" that maybe hogging resources. Close those you don't need while running disk clean-up. At least that's a start, I rule out any other glitch for now. If that still fails, try the above again only allow the disk cleanup to run overnight, while you sleeo to see if an error message pops-up or it actually finishes. You need the windows taks, any other tasks, like CD s/w, firewall, etc can be off while you run it. If you have an always ON broadband, shut it off for the duration.
For some reason when i try "disk cleanup" it gets stuck on "calculating" mode for compress old files. I've let it sit for hrs and it never got pass that. At times I can't even get the Disk Cleanup to even come up. Please help me resolve without causing any harm to my computer. It's on windows xp (with service pack 1)