It occurs to me that it could be a reference problem. Open the VBA editor on the 2003 machine and go into Tools/References. See if any of the checked references at the top say "MISSING". If so, uncheck it, recheck it, close and open Access and see if that fixes the problem. If none are MISSING, check any reference; close and open Access; then uncheck it again. This will force Access to relink the libraries.