I have now tested a workaround. First convert the database from file format
2000 to 2002/2003. Enter VBE but don't try to load or display the userforms
using code. Now make new userforms using similar names for each old userform.
Open each matching pair of userforms and copy all controls and code from the
old ones to the new. Remove the old userforms and rename the new ones with
the old names. Remember to save the database from time to time, but never
save the old userforms. You will get a saving prompt where you can disselect
the old ones.
This strategy works but still you cannot export the new userforms and then
import them back again to a database in 2002/2003 format. In that case you
will experience the same problems as importing from the original userforms
from Access 2000 file format.
I suppose this was not what microsoft intended with the VBE import/export
functionality. Does anyone know whether this problem affect Access 2007?