After spending hours tearing my hair out I thought I should share this gem of knowledge:
In Access XP (2002) the ODBC connections I set up through pass-thru queries to Sybase ASE 12.5 (ODBC driver: DirectData 4.2) kept being dropped and I was prompted for my password for every query that ran on the server
After altering the DDE refresh properties (which had a temporary effect) I noticed that the connection string contained 'DB' instead of 'DATABASE' and I changed it. This fixed the problem.
(Note I did not want to hard code the password in the connection string because it is poor security, against my firm's policy and has poor performance because the connection takes time to be reestablished each time it is needed.)
If anyone came up with a different solution I'd be interested to hear about it!