Wireless Fio programming with Mac

Has somebody got it working? I've done everything according to these instructions

I'm using the Sparkfun XBee Explorer USB. I have tried everything with and without the jumper soldered. I also tried manually reseting the Fio at various times around the time I hit the upload.

According to this article

you should also solder a jumper on the Fio. On my Fio it is soldered at the factory, haven't tried to open it.

I seem to have to XBees configured right, but when I try to upload, I get this:

Binary sketch size: 1042 bytes (of a 30720 byte maximum)
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_recv(): programmer is not responding

and then "Problem uploading to board". I get exactly the same even with the Fio turned off. However, I get activity on all the LEDs on the XBee Explorer, and RSSI (and the LED next to the reset button) on the Fio as I try to upload.

Whatwhatwhat? Just after writing the above, I tried one more time, and the upload worked! I haven't changed anything, even the Arduino software is still running in the same window. I have tried for at least fifty times before. I now have the jumpers closed on both the XBee Explorer and the Fio.

Hope somebody has some idea what's going on!

Now I'm suspecting my laptop, an early 2006 Macbook. Sometimes the upload works, sometimes not. Guess I was running too much stuff at same time when the upload didn't work at all.