Among a few other suspicious voltages:
IC9 pin 3: 5.9V !!
This looks bad. Your 5v regulator IC11 should be putting out 5V, not 5.9V
These regulators can only supply voltage, and cannot deal with
something that tries to pull them higher.
Perhaps a current path somewhere between +12v and the 5V rail?
Re-check that the regulator is actually providing +5v at its output.