Just been trying to update some e-mail contacts, & everytime I try to edit, the message 'Windows Explorer Not Working'pops up. I get the option to search for solution online or restart WE, neither works. Haven't tried a System Restore yet, but wondering if a Windows Update is the culprit, having said that my laptop is fine but pc is not, both Vista.
Try a System restore in safe mode - it's likely something has changed on your PC this should sort it out.
Before you do this and in case you don't want to do this when the message "windows explorer is not working", click on Details and see the file name mentioned - possibly it is a file you will recognise you have installed recently. Uninstall this or delete if it doesn't have an uninstall option