If it happened to you once, you'll most probably going to experience it very soon again! At least that's my experience. Reinstalling each and every time you see this problem is soon going to be major PITA.
There is a procedure to "heal" the allegedly corrupt System file (along with other Registry hive files) on Microsoft site Knowledge base - if you happen to see this again you should look for it, rather than reinstall
Procedure is NOT simple, and takes 5-10 minutes and 2-3 restarts to complete, but once you finish - you have your old system back, without losing anything, certainly better than having to reinstall from scratch.
If you can't find the procedure I can look for it for you.
O.