Try a different USB cable? Make sure the board is plugged directly into the computer, not through a hub (or keyboard, etc).
Which serial port are you using?
Do you have any software that could be accessing serial ports? For example, anything to synchronize PDA's or other devices, or a cellular internet USB dongle, etc. Try disabling that.
I have the same problem with my MacBook Pro, OSX 10.5.8.
Did this get fixed? It seems that it is a common problem - many postings
I had been using the rev 0019 IDE with a Duemilanove for many months when the problem started.
The upload error message
"avrdude: stk500_recv(): programmer is not responding"
appears twice after the binary sketch size is reported after an upload is started.
I had updated to 0022 a couple of weeks earlier. I had run the board off of a 9V battery the day
the problem started. Since then I have tried several cables, moved to different USB ports, ordered a
brand new UNO, reverted back to rev 0019, reinstalled the USB driver several times. The test sketch
is plain old "Blink". No luck.
I'm having the same connection problem with the UNO board on my MacBook OSX 10.5.8 and Arduino v0022.
How can I check those processes that deal with USB based cellular internet access pen? How do I disable them?
This is last thing I need to try, otherwise I'm returning the board and give up on the arduino stuff. Shame!
The same Uno board and the same USB cable have been used on my MacBook 10.5.8 but running
the arduino app (version 0022) on windows XP through VMWare and it works.
You (developing) guys need to sort this out: it's not the board, nor the USB cable. It's how you interface
and access the USB port on the Mac OS X.
I am glad to learn that VMWare on the same MacBook works.
It seems that Apple had an operating system update that caused the USB timing to the Atmel to change? Why else would several boards work one day and not the next. I can see that I am connected to the Arduino, just am not now able to upload changes. I do not know how Mac OSX users are supposed to resolve this. Are there any upload timing variables even accessible that can address this?
After two weeks of development time lost and no reply from the developers I would gladly scrap Arduino and go with another controller, however I have too much time and hardware invested, considering that a simple SW fix from Arduino is surely possible.
I just went through all of the Arduino pull down menus and changed the Serial port from /dev/tty.usbserial to /dev/cu.usbserial and was able to upload a Duemilanova. Uno requires /dev/tty.usbserial.
I also run into that same error... only getting the sketch from the day before and not being able to upload a new sketch.
OSX 10.6.7 - Arduino Duemilenove - Atmega 328
However, it was very simple:
For some reason, when I open Arduino the serial port had changed.
I changed it back again (Tools/ Serial Port/ /dev/tty.usbserial-...)