I would start over from the beginning and make sure you do all this FIRST. You have to be completely prepared for SP2 which means. Spyware free, Adware free, virus free BEFORE you install SP2, Also go to this link from Microsoft which also has links inside of it that will tell you what to do to prepare, including programs that are known to have problems which you may have to patch BEFORE you install SP2. Also go to your computer manufacturer's web site to see if any programs that came with your computer (non Microsoft programs) that need some sort of a patch BEFORE you install SP2. After all of the above, you should have no problems. Here is the Microsoft link. Hope this helps.
I have been having an ongoing problem - my system crashes when installing certain patches from Windows Update. The latest being SP2 - it downloads and during the install phase the system crashes.