Windows 7 Explorer has stopped working error plz help

When I go into Default Programs in the Control Panel and click 'associate a file type or protocol with a program', I get the message 'Windows Explorer has stopped working'.

When I restart Windows Explorer and try again, I just get the same message. Any idea what could be causing this and solutions?
I'm running windows 7 ultimate 32bit .

Does anyone have a solution ??

OK. Let say Explorer is corrupted this is what I would do.

1. If I had a restore point prior to this happening trying that first.

2. If that is not possible i would access the Command Prompt as Adin and type SFC /SCANNOW
Post results here

3. I would install the Win7 disk and try a repair install.

Anyone else have any suggestions?