Update: If your Orion software has been updated after April 2014, you can try going to the Help menu in Orion and clicking “Check for New Contacts and Matters.”

Each User actually has a local copy of the contact and matter lists on the workstation, and that is what we read rather than going to the server every time a Client-Matter number is needed.  It sounds like your local copy is corrupt.  You can do the following.

1.  Close Orion Desktop.

2.  Open Orion Administration.

3.  Click on System Information (in the Orion Side Bar), and then over to the right, double click on System Settings.

4.  Once System Settings is open, access the Other Tab.

5.  Click on the FORCE CACHE TO EXPIRE Button.

6.  Close System Settings and close Orion Administration.

7.  Open Desktop back up (it will take a little longer to load because your local copy of files is being rebuilt).

8.  See if you can use the Client-Matter number without error now.

NOTE:  The FORCE CACHE TO EXPIRE Button impacts all Users.  The next time each User opens Orion Desktop, the local copy of the files will be rebuilt.