I don't really like the idea of Formatting computers off coz of the bugs, but since you have many damaged System files, Save all your data into a CD or another Harddisk, if you have one. Format thru XP. Not just Install XP on top of this OS, just FORMAT IT CLEAN. would be much easier, rather than trying to update, scan, repair. but again i tell you, i don't really like the idea of formatting computers. but could be easy for you.