Dan, Agree good time to upgrade.
1 - Any reason that you know of to just upgrade to 10.2.0.2 and not to 10.2.0.5?
- looks like 10.2.05 oracle client has been certified on Windows 2003 Server, so should be okay
2 - I have never installed the ODAC on any machine requiring connections to Oracle. Always the Admin Client. Is there something I am missing by not doing so?
- ODAC supports .Net framework via Oracle Data Provider for .NET, Oracle Providers for ASP.NET, ODBC, etc. Installing ODAC may be a bit over kill, but appears to have been part of the solution in resolving the disappearing dll’s in some instances. Totally understand wanting to be cautious when introducing new variables into production environment. So, one step at a time is always best.
Best of luck in resolving this issue and keep us posted.
prv.