I just got burned with the .NET Oracle driver, we used in our C# ASP.NET apps. Turns out, the .NET Oracle driver, automatically turned the user id and passwords into Upper Case when passing them to Oracle, since in earlier versions of Oracle, they were case-insensitive. Well they upgraded to Oracle 11, which does make user ids and passwords case sensitive, and suddenly everything broke.
YIKES! Can you just use a generic ODBC driver? That would give you the password casing you need. Of course it would be slower, being ODBC, you couldn’t count on the Oracle optimization..... Or are you locked into some of the Oracle functionality in your current driver?