To resolve ASP.NET CS0433 compile errors resulting from a changed code-behind, simply do the following:

1. rename the Bin directory (may need to wait for the processes inside to finish talking to it)
2. visit page in question (will result in an error, just ignore)
3. rename Bin directory back to Bin
4. visit page in question again

Ta da!. =)

Thanks go out to David Woods for this solution.