Message:Failed to connect to database 'MainDB.gxdb'.
(ErrNo:-2147467259 Details:Could not use ''; file already in use.)
Cause: From the error it seems that the currently logged in Windows user on the machine on which you receive the error does not have Modify/Write permission on the folder in which the Sohodox databases is located. (This is usually the 'C:\Sohodox databases' folder).
Step 1: You will need to share the 'C:\Sohodox databases' folder wih the Windows user and provide Change permissions on the Share as well.
To do this...
If this does not resolve the issue then move to Step 2
Step 2: If you are using an MS Access based SOHODOX DB then sometimes the Access based gets locked by a Windows user accessing the shared file. You can restart the server to resolve this or if server restart is not possible then you can find out which Windows user is accessing the shared drive and restart the client machine which is accessing the file. Start SOHODOX you should now be able to access it.
Note: If you are using Windows 7 or Windows Server 2008 then there is a built-in program using which you can find out the machine which is accessing the shared drive. More information on using it is available here...