Microsoft Business Solutions-Axapta 3.0 is now part of Microsoft Dynamics AX 3.0. All references to Microsoft Business Solutions-Axapta and Microsoft Axapta pertain to Microsoft Dynamics AX.
Error - "A Runtime Error 339. Component MSMASK32.ocx or one of its dependencies is not correctly registered; a file is missing or invalid" - occurs when you go to File | Open | Catalog.
Go to Start | Search | For Files or Folders and search for the MSMASK32.ocx file in your Windows/System32 directory.
If you do not locate this file, copy it over from a working workstation and paste it into the Windows/System32 directory on the workstation with the error. Make sure to register the file by opening it with the Regsrv32.exe file located in your Windows/System32 directory.