Computer crashed and fix-it utilities 11 didn't reload fully. Need to enter product key and reinstall

I'm not having problems wth the Fix-it 11 my problem is with the System Mechanic I got last week. It refuses the Product key but still does a better job than anyof them. It just comes up and says product key not valid. It's the one that came with the CD and I've cut - paste and typing , still want take it! I'm not having problems wth the Fix-it 11 my problem is with the System Mechanic I got last week. It refuses the Product key but still does a better job than anyof them. It just comes up and says product key not valid. It's the one that came with the CD and I've cut - paste and typing , still want take it!