dlloyd:
Other possibilities ... Arduino clone, faulty Arduino, faulty serial pins, wrong type of USB serial adapter (type or level mismatch - ttl/rs232/3.3V/5V), faulty USB cable, USB cable too long, using USB Hub without adapter connected, incorrect serial settings in OS, etc.
It's not a clone. Using one from the Sparkfun kit. Tried both serial settings with identical results. Don't know how to attack the other issues you mention. Cable works fine if I include a Serial.println(); in code. Also blinking diode sketch works fine. May go out to see if I can get another Uno at Radio Shack.
Any other suggestions?
Don