Interesting, what happened to the server and how did you correct it? Did you have to restore to a new server? Reinstall EPDM or SolidWorks on the client? I'd look into "C:\Program Files\Common Files\SolidWorks Shared\swdocumentmgr.dll" as possibly old version or something off about it. Usually an easy fix by repairing SolidWorks.
The server lost power and the battery backup failed so in essence the plug was pulled, once we had sorted the power issue they came back on line but apparently that was not the issue. I have fixed the issue now but just to let you know you were correct the issue was with the SolidWorks Document Manager. I re-installed it and now it’s working fine.
Thanks for your response.