Thanks to all who posted. After a lot of Googling, I found info on how to activate the Administrator account in Vista - and of course I thought I was home free. Not in this world. Apparently, the permissions are screwed up on this set of files, and nothing is going to fix it. Fortunately, the files are on a partition which I use for temporary storage of large amounts of data. So, I guess I'll move everything else of value off the partition, and reformat the damned files out of existence.
Again, thanks to all who posted. At least I did learn how to activate the Administrator account (and to disable it) in Vista. So all is not lost. By the way, some forum members might be surprised to see how much inaccurate technical stuff exists out there in www land.