sfc/scannow wont finish

Guess I should start at the beginning of this. About a month ago I went on a real "theme" frenzy. Downloaded some themes from sites I trust (deviant art, win7 themes etc.) tried a few and kept them. One in particular i liked alot but for one thing... the start orb on the taskbar. I changed my start orb a long time ago to a computer start button and love it. Anyway, that particular theme wouldnt let me change the start orb so I switched back to one of my personal themes , when i went to change my start orb again....... I lost my whole desktop! Taskbar,start menu, everything , just a black screen with a cursor. Needless to say I was in a panic. Could not call up task manager or anything. Tried starting in safe mode, tried system restore,nothing worked. Finally I just went ahead and reinstalled from my recovery partition (Vista) then upgraded to win7 again. Since then my machine has been buggy and tempermental. After I got it stable enough to feel comfortable to use I've ran sfc/scannow multiple times. The first few times it found corrupted files (some it could not fix), but the last few times it said all was well. Thinking that all WAS well I , foolishly, tried to change my start orb again. Same thing happened. Well, now I knew how to call up task manager by shift/ctrl/esc so I did and ran sfc/scannow. It worked, got my desktop back. Tried my start orb changer AGAIN. Same thing, this time when ran sfc/scannow it got to 45% and stopped. Said there were corrupted files it couldnt fix and stopped. Tried it again and it said the same thing at 45% again. Now my question/problem is...... Why would it stop? Another reinstall is sorta out of the question now seeing how my optical drive is not working. (would rather not be stuck with Vista for a month or so til I can get a new optical drive) Is there another way to restore corrupted files besides running sfc/scannow or reinstalling? I am very leery of doing anything "dangerous" now because I'm "snakebit" to say the least! Any ideas or suggestions? Thanks ahead of time. Win7 H.P.x64 (version 6.1.7600 Build 7600)

Can you do a System Restore to a known last good point?

Yes , Thats how I got it back to where it is now. But when I try to run the sfc/scannow it just stops at 45%. Machine seems to be working alright....... but the scan not finishing has me nervous to say the least. You think I should try to restore to an earlier time?

Yes, try roll-back to a time before you changed the Start orb - that seems to be where you started having problems?

Will do. I'll just take it back to the earliest time on it. (yeah...... I do delete older save points......... I try out lot's of programs and keep very few, so end up with many many restore points) Will post back later and let you know if the sfc/scannow is back to "normal".

Well, it worked. Restored to earliest point and then ran sfc/scannow. The scan ran 100% , found corrupted files and repaired them. Prior to the restore I also ran a start up repair , so one of the two fixed it. Thats a real load off my mind! Thank you both.