This may not much help, but try re-installing the whole programme, if you have a genuine version, this should sort all the problems.

Wassail! Chris

PS. Save all your Raw/Tiff/jpeg files to CD monthly, then you will have a permanent hard copy archive. Which will not only keep your images safe from loss of a hard drive, but if you don't like what you did in the digital darkroom, on your hard drive, the original is always there to have a bit more fun with. Before you re-install PS7, archive all your images to disc.