Doug
Most common error in running SFC is forgeting to include the space between the c and the / (sfc /scannow)
There are also (2) two (n's) in /scannow
I'll search a little to discover common problems that would cause the symptom you describe of the "sfc thing isnt working it goes to the black thing then dissapears"
In my use of sfc /scannow … the black DOS command screen opens for just a split second then closes, followed by a windows variety progress monitoring screen about 1 inch high and 3 inches wide.
This screen is titled:
Window File Protection
"please wait while windows confirms that all windows protected files are intact, etc."
below the title and message is a "progress bar" that tracks left-to-right until SFC has completed the scan.
If missing or corrupt files are located, SFC calls for the XP installation CD, and thereafter reads/copies/replaces missing or corrupt files.
If you have other windows or application programs open during SFC, the Window File Protection screen may become hidden behind one of your open applications.
Recommend that you close all window before running sfc /scannow
See ya tomorrow.