I have been having problems with connecting to the Windows Update site. Tech support says my WUPDMGR.EXE file is corrupt and needs to be replaced by system file checker. The tech went on to say that I needed to do a repair installation because when I typed in sfc in the run window, (not sfc /scannow) a black screen appears for a split second then disappears. So what happens when you type in "sfc" without the quotes in the run box? Do I need to do a repair installation?