Scenario: Service bureau CSR working remotely but connected to the office via secure VPN, running the Evolution desktop GUI client while logged into a Windows terminal services machine. Evo runs fine, but when trying to save files from the application, the save-file-as dialog box would not show any network mapped drives, only the local ones.
Hmmm.
Resolution: uncheck the "Run this program as an Administrator" box in the properties for the Evolution.exe:
We're not sure how this got set in the first place, possibly it was the installer taking special note of terminal services, but unchecking this box made the problem go away.