Today, Steam put up a small message box saying something like "optimizing your files for performance" with only an "OK" button. Out of morbid curiousity, I did Skyrim->properties->local files->verify, and it always says 1 file failed verification, will be reacquired.

AFAICT, nothing is downloaded. Every time I re-verify, it says 1 file failed, but never says which one!

I tried deleting the Interface and Strings data folders, then it says 8 files failed, and reacquires them. But there are only 7 files, and it goes back to saying 1 file failed.

What the heck is going on? Should I play and ignore it?

I'd say if it ain't broke, don't fux it.