Yeah...with just the standard updates from MS....I agree with you, that should have not happened. With the update, did you get the KB 2919355, about 900 mb. If so, that was the update to 8.1, called 8.1 update 1 and a lot of users are having problems with it. Either not updating at all, partially updating or in some cases like yours, messing up the system file. More than likely and clean install might be in order for your particular situation.