...well, that was just my guess. I've seen the problem about a dozen times with ~20 users over the last 3 years - but never with a fresh installation. It usually happens when moving from one version to another, or when opening an old package.
Another wild guess: When you imported that wire file, maybe KS added a material it found in the .wire? (we pretty much just use KS on Maya files here, so I don't have much experience importing Alias)