Here is the setup, I have written a module, that uses client callbacks when user presses a button.  It works fine, until host uploads / upgrades different module to dnn web site totally unrelated to module in question.  After that, whenever user presses a button callback triggered on client side, but always fails.  In the debugger, callback handler (on DLL end) never gets called.  The problem goes away after user logs off and re-logs in.  The only thing I have found is HOST_ALERT site log message that just states module installation steps.

Any ideas on where I might have to look?