On a test machine I did an upgrade install of Vista. Windows explorer keeps crashing (although safe mode seems stable). I removed the drive and installed Vista on a clean drive and it is working perfectly on the same machine. Any ideas to diagnose and fix explorer in the first install? Having to reformat is not a problem since there is nothing to lose on that drive but I would like to either fix it or uninstall--which I suspect is impossible since it was installed over xp.