Move Selected Item(s), Reply, Reply To All, Forward, Spam, and Launch In A Separate Window buttons suddenly greyed out

[Hebz]

I am using Zimbra Desktop 7.3.1 GA (build 13063) and the Move Selected Item(s), Reply, Reply To All, Forward, Spam, and Launch In A Separate Window buttons have suddenly been greyed out (made unavailable) for a certain email address that I have been able to reply to (and move content received from) for a long time. When I double click on the email instead of opening it with the thread details in a smaller window above the window with the email bodies it opens a new Reply To All composition, so at least I can reply that way. I still cannot easily move the content to it's appropriate folder. I have not made any setting changes or software upgrades since the last time I could do this. Any assistance on resolving this would be greatly appreciated.