We had a user who could no longer see the files in a certain folder in
Explorer. They would appear in a command prompt screen but not the
Explorer GUI. Sub-folders showed up but not files.

I checked from my PC and the files showed up fine. Determined the main
difference was my machine was on client 491SP2 and the user was still on
491. Upgrading the client to SP2 fixed it. Is this one of the known bugs
fixed in SP2?