did I destroy my board?


I have a duemilanove atmega328 board, and has since been working ok, but yesterday I think I might have destroyed it.

It was connected to a breadboard with an external power supply, and when I connected it to the computer to upload the corresponding programm nothing happened - I just got the error message: avrdude: stk500_recv(): programmer is not responding.

And this happens ever since, when I connect the duemilanove.
I also have a nano, which doen´t make any problems, and continues to connect flowlessly.

When I plug in the usb-connection to my macbook, the red led “L” and the green power-led both go on, and remain on. The arduino-environment on the computer, seems to realize the connection, because when I change the usb-port, I get a pop-up, that a new serial port has been found, and connected to.
When I try to upload, the RX-led blinks three times and nothing else happens, and the error above appears in the arduino status window.

Is it - is it broken, destroyed, kaputt? Is there a way to check the board-hardware, if it is physically ok, or destroyed?

Any hints?

The arduino software version is 1.0.1 and is running on a macbook pro with snow leopard. Drivers & co. should be ok, because everything was working without problems till now…

Many thanks in advance - micthenic