VERY weird, windows xp, multiple things wont come up

I'm at my grandparents house until Sunday, and my grandfather wants me to take a look at his computer. He had a virus some time ago, and now it is completely cleared. But! after looking at his computer (XP) he has less than 400mb left on a 200gb hard drive. So I went to delete some of his history (over 10gb of temp files) to clear up the issue. Trying to delete it (he uses IE) through the tools>internet options... it just stops. Nothing happens, clicking on internet options actually causes the pulldown menu to close, and the options never open up. After some thought I tried to restore his computer to an earlier date... And this does EXACTLY the same thing that the internet options did in IE. It just closes the window and doesnt do anything. Looking at msconfig there is nothing suspicious running from startup (only 5 normal things).

 

As a lot of malware can hide and does have hidden processes, I would recommend going to the following link and following all instructions. http://forums.majorgeeks.com/showthread.php?t=35407. Hope this helps!