A family of Microsoft relational database management systems designed for ease of use.
Thanks I found the answer to my problem in an Autodesk support article. The problem was with some library files which are stored in the c:drive under "Documents and Settings\user\Application Data\Microsoft\Forms".
Once I deleted the two .exd files in this folder, closed down and then ran the AutoCAD software and VBA manager command again, it worked. It is something to do with Windows or Microsoft updates that change the runtime files in Visual Basic 6.0 and they don't talk to the older library .exd files anymore. Once you delete the old ones and run the software it creates new ones which are compatible (I think... not being an I.T person).