Ah, yes, the constant complaint. When you come up against a situation where you've checked off everything you can on the task list and no one has anything to say to you besides "What's up?", it usually means either there's a puzzle you were trying to avoid or have forgotten, or there's an area you haven't explored yet. In any case, here's some things to try if you're stuck.
-- Talk to everyone about everything, including on the phone.
-- Check the Messenger program in the museum office and the notes on Grigor's tablet for new messages.