With ASP.NET set to impersonate a non-anonymous Windows account, I found the Inmagic ODBC driver flipped a henry when asked to perform a SELECT MAX statement. The error returned was "ERROR [S0000] [Inmagic, Inc.][DB/Text ODBC Driver]Unable to do ORDER BY".
It turns out that read/write permissions on the Documents and Settings\[machinename]\ASPNET\Local Settings\Temp folder are required (this is an XP machine I'm talking about). (Thank you Filemon.) I assume the ODBC driver requires some workspace in order to sort the records and pick the most maxest one. I don't know if this is the case with any ORDER BY clause or what. The ASPNET account has full control of that temp directory by default. Giving the Users group read/write access cured this otherwise intractable phenomenon (the Windows account in question was a member of the machine's Users group).
If you're wondering how to flip a henry, use your imagination.