I'm facing this problem again and again, but can't find any solution (except mine, which is not as a good one I guess). Don't know why, sometimes Flex Builder executes old source codes after making changes. While debugging I see how it steps through a source (e.g. changing local variables) which does not exist (even if I delete all that block or function). My way to solve that is to delete the project (backing up the source codes of course) and create a new one, add the backed up sources to the project and rebuild. It starts to work as it should work, but this way is not as comfortable, especially if sources are on a remote machine and you need to configure .net back-end. Anyone knows how to solve?