I had my external hard drive attached to a friend's computer while they were installing the automatic updates in windows xp. When I got home I found that my hard drive had a 2 folders that I couldn't delete both called sp1 but in different directories. I can't remeber the original path that they were in because I changed their names in an attempt to delete the folder. I can't rename, delete, access, or move these folders. I have tried to delete them via command prompt, safe mode, by changing the name of the path, using deletefxpfiles, and by using command prompt while explorer.exe was ended.
You may have tried this but if you right click on the files concerned and select "Properties" there are tick boxes at the bottom of the window which opens. If the file is ticked "read only" untick it and try again.