Arduino won't upload

I just got an Arduino Duemilanove (ATMEGA 328), which I am using with an iMac running OSX 10.4. I have installed FTDI 2_2_10 driver and I have selected my board and the /det/tty.usbserial-A9007LbN serial port, but whenever I try to upload it says "Build folder disappeared or could not be written." I can't find any reference to this problem on the web. Thanks.

I'm in the same place ... however, you may be running the app from the mounted directory. Try copying to the desktop and run it from there.

That worked for me.

You’re a genius! It works perfectly. I can’t wait to start using the Arduino. Thank you.