I get the errors when a function is called from within my queue, which operates its own (single) thread. The function goes awry when it tries to call the instances' private (or public, or superclass) member variables. In my case it tries to up a counter (_cnt++). There is no external interferance with these variables.
Now you lost me. I thought you got the error messages when you were shutting down Roxen? Are you saying you get the errors while your server is up and running too? If so, the situation is a bit different.