Download TREESIZE FREE (from Jam Software, and it's free as the name suggests) and use that to see in what folders you disc space is used.
The nice thing about the latest version that - as soon is it encounters the System Volume Information folder (that normally is inaccessible) - it asks you permission to switch to administrator mode on Windows 7 (maybe on Vista also, I can't check) and then analyses that also. To see that folder in Windows XP you have to use the grant command (in the command prompt) or boot from a Linux disk, which is much more work.
Warning: don't delete files or folders when you're not absolutely sure it can be done without harm. In case of doubt: post here to ask.
This is only a way to find out about the disk space. If that's related to your other problems is far from certain (but not impossible).
My computer has been doing strange things lately, like being overly slow no matter what I'm doing, giving me a spinning circle, etc. I have done a disk clean-up, deleted browser history and did a disk check.
It is still doing all of the above. I noticed my C: Drive says 9.82GB free of 138GB. Can you tell me how I can check this? I have no idea why as I haven't added any programs or software.
I would appreciate any assistance you can give me. I do use my computer to work from home also.