A few days ago a colleague asked me, why i use Notes only on my main display of the Macbook Pro. I didn’t remember the reason, but today i discovered it again.
When i move my Notes Client window (8.5.3) on the second display, i can’t use column sorting when clicking on the column header. Then i moved the window bar (File, Edit, …) of Mac OS X (Lion) on the external monitor too and … I’m able to sort my inbox, when i click on the column header (like subject, date and so on).
I played around a little bit and tested some other Mac OS Clients in the office and i can reproduce it. Only on displays with the windowbar i can change sorting, when i click on the column header.
Update
IBM acknowledged the problem: http://www.ibm.com/support/docview.wss?uid=swg21584595&myns=swglotus&mynp=OCSSKTWP&mync=R

Sounds like a PMR should be raised. This is surely an edge-case for which there was never a test-case.
This might be fixed in Notes 8.5.4. Try 8.5.4 if you can access the beta builds now.
I can access the beta build and i get the same error.