You can test and see if it's a corrupted or malware infested OS problem. Which is what it kind of sounds like. The 8GB low HDD disk issue can be malware related.
I know you mentioned you've had that laptop for two years. Did you get it used?
Make yourself a bootable CD with an OS other than Windows.Ubuntu Desktop
It's Linux, not windows, but I think it will boot off the CD without needing to be installed on the HDD.
If you need to rescue important personal files or data you can use the Ubuntu file manager.
It works enough like Windows I think you'll be able to figure it out.
If Ubuntu runs nicely on your laptop and you're not having the type of problems you mentioned? I think you can probably figure it's a bad OS or Malware problem.