I've also tried deleting these folders in safe mode, command prompt and DOS. Through those mediums, the computer gives me a Data Error (Cyclical Redundancy Check) error. So basically, I can't install VS.NET anymore, and I can't get rid of around 10 folders from my drive.
From your description I'll take a stab at a couple of issues you may be having. First, it sounds like CD 4 has data errors on it. You should contact Microsoft for a replacement. As for manually deleting the folders, you should be able to do that. If you can't you may have hard disk errors. Any time you are getting CRC errors you need to see what you can do to get the disk fixed.
This was first published in December 2003