Call Sony Tech Support at 1-800-222-7669 and describe the problem. I had the same thing. They said the problem is in the memory and try a 2 minute power off reset first. This did not correct the problem. They then advised to return the unit and exchange for another one. Apparently, a number of units were programmed with corrupt software. Unless you can reprogram it yourself, you need to replace the whole thing. Good Luck.
Greg Robinson, San Jose CA., July 2007