I have already solved this problem, but just posting to let other users know.
I had just set up a new voicemail user in unity and was running into a problem where after clicking on the envelope icon on a 7945 phone, the user could put in their pin and authenticate, but when they went to view a voicemail message, the server would come back with "searching... there was an error displaying your message" or some such text. The voicemail worked fine from another phone, and worked fine in their email mailbox, so it was a bit puzzling.
This was caused by the default for "enable phone view" under the Edit -> Phone Menu, menu in unity. The default has been changed between versions and had to be reset to have the checkbox not checked.
This was set as default for all accounts after the upgrade. we are currently running Cisco Unity Connection version: 11.5.1.11900-26 but i don't remember the previous version we have updated from.
FYI, hopefully save someone some time.
