Since I'm not seeing issues like this I'm assuming these are computers on an active directory... I remember XP having a few fun issues like this when a GPO refreshed links to a file that didn't exist and froze for a moment trying to resolve them.
I get this all the time without being on an active directory. It's nothing network related from what I can tell. The explorer tab just stops being interactable seemingly randomly. Closing and reopening the tab works around it.
