Late 2010, I purchased and had installed a Rheem furnace & AC, Humidifier, Air cleaner and Rheem thermostat (RHC-TST550cmms). Intermittently, since installation, I find a message on the thermostat saying "System Config Changed" when in the "Heat" mode. The HVAC contractor comes and deletes it somehow and says that Rheem's engineers are aware of the problem and are working to correct it (for over 2 years). I am frustrated by their failure to affect a solution and ask if anyone has had a similar problem and what they have done to solve it? Thank you.