Folders Slow To Load In Same Window

I've got a Dell running Windows XP Home with a very specific but hard to search for problem:

1. Opening any folder in the same window (folder options set to 'open folder in same window') is incredibly slow (minutes) but opening any folder in a new window or setting folder options to 'open each folder in a new window' is perfectly normal.

2. Internet Explorer takes minutes to load a new page (you can see that it's loaded in the staus bar but you can hear the computer grinding for minutes until it displays the new page). Firefox is just fine.Both of these issues appeared at exactly the same time.

3. Probably unrelated but windows installer is not functional? (I haven't looked into this much yet)

Nothing unusual is running in task manager and none of the normal processes are running extra hard. I have done the basic spybot, adaware, and regfix scans with a couple files removed but none that affected this issue.