So basically, Windows is very unresponsive, and you can't really do anything?
Sounds like a software issue, but it could be hardware, you never know. I would back things up ASAP just in case.
For starters, boot into safe mode. Hopefully in safe mode things work a little better. If so, that is going to have me leaning toward software issues. How to boot into safe mode:
Restart your computer.
When the computer starts you will see your computer's hardware being listed. When you see this information start to gently tap the F8 key repeatedly until you are presented with the Windows Vista Advanced Boot Options.
Select the Safe Mode option using the arrow keys.
Then press the enter key on your keyboard to boot into Vista Safe Mode.
When Windows starts you will be at a typical logon screen. Logon to your computer and Vista will enter Safe mode.
Do whatever tasks you require, and when you are done, reboot to go back into normal mode.
In safe mode, I want you to run full antivirus and antispyware scans, and report back with the results. Good luck