avrdude: stk500_getsync() attempt (n) of 10: not in sync: resp=0x20 (Again!)

I have a Freeduino USB board which is a Duemilanove compatible with an ATMega 328P chip. Off and on, I have been having problems connecting to the board. Currently the errors I am getting are “avrdude: stk500_getsync() attempt (n) of 10: not in sync: resp=0x20”.

Here’s the short, recent history.

Yesterday in the morning, the board was working fine. I compiled and uploaded a program to count down from 9 to 0 on a 7-Segment LED. Apart for a couple of minor bugs (typos) the program worked.
Somewhere along the line, it stopped connecting and no program would upload (they compiled just fine). I started getting errors in the IDE and in Windows (USB device not recognized
). In Device Manager I got the error “Device Descriptor Request Failed”. I tried resetting the port, disabling then enabling the device etc.

Finally a reboot fixed the problem. For a while. The problem occurred again and this time a reboot did not fix the problem. Note that the uploaded program described above continued to work and I could see the LED countdown from 9 to 0 in a loop.

So, I decided I would not use USB anymore for power since perhaps that was conflicting with the USB and switched to eternal power (12V 1A).

On plugging in the board to the power, the above mentioned program (countdown) continues to work, but the IDE will not communicate with Board and I get the error message described above. Also, the green light comes on always and the red light flashes for a few seconds when I connect the board.
I disconnected all the wires (for the LED) and still no luck.

I noticed also that the port now shows under Ports rather than under USB in Device Manager.

I then did the Loopback Test described at http://forum.arduino.cc/index.php?topic=73748.0 and the board passes that test. I have tried all the other solutions (at https://www.arduino.cc/en/Guide/Troubleshooting#upload as well as elsewhere) I have come across but nothing has worked.

Any suggestions?

I bought a new Arduino Uno yesterday and tried that. It works fine (at least for Blink).

I tried the same cable with the Freeduino, but still doesn’t work.

Since the Board works and the cable works, and the Chip works (I am assuming this since the 7-Segment LED was counting down) what else could be wrong?

Please help. Any suggestions welcome.