If you are having trouble switching from Compiled mode to Interpreted mode in a 4th Dimension database here is a tip that might help:
When you quit a 4D database 4D tries to kill all running processes. When you switch from Compiled mode to Interpreted mode, 4D runs through the same procedures it would use when quitting the database.
One problem that can occur is that 4D cannot kill a paused process. When designing a database that uses the PAUSE PROCESS command you must keep this in mind.