Outlook - Help diagnosing/troubleshooint Operatoin Failed messages, etc.

Noticing a couple users on same server as me (Exchange 2010) just running into random issues every once in a while, like getting "Operation failed" when sending a message or replying, or trying to accept a calendar appointment.

Are there any diagnostic/logging tools I can run on the client side that will help diagnose when they run into these issues?

Unfortunately I can't shadow them all day to wait and see what happens, but I trust it is not end-user at this point.
Often having to close and re-open Outlook or restart the computer and reconnect to get things to work. Some times that doesn't help though.

Exchange 2010 and clients are Outlook 2013. They are in Online Mode so there's no offline cache or ost files.