Problem:

User gets the error "System Lock Reset", and can no longer type in the Mainframe Display.

Resolution:

If the system is locked, reset it by pressing CTRL R.

This is not a Rumba specific issue, and occurs when something is typed in to a field that does not permit it.

This error is a reflection of mainframe behavior, where trying to type in a field where you cannot enter any characters - the System Lock Reset message appears.