Wow, being new to the RV community, I am totally impressed by the experience and knowledge of the responders to my initial post. I talked to the people at Xantrex and was told that a high reading is normal when there is no load on the inverter. I guess that the clock on the microwave is considered no load. The Xantrex folks suggested that I put a load on the inverter and recheck the voltage. It worked. As soon as I put a load on the inverter, the voltage dropped immediately to 120.
Now I have to figure out why my Norcold 1200LRIM refrigerator will not run on the inverter. It works fine on the gen set and shore power but not the inverter. I have been advised to not use the LP setting while driving down the road. Thinking that the no load high voltage on the inverter might be the problem, I put a load on the inverter and the refrigerator still beeped and flashed a "no AC" message. My next step is to call Norcold. As a side note, my refrigerator was manufactured after the recall group.
Thanks again to everyone for their help and wonderful technical expertise.