I just put together a Bare Bones Board from Modern Device. I installed the arduino-0010 software on my Windows XP SP2 machine, and I'm using an FTDI USB cable that I also got from Modern Device. After plugging in the USB cable on the computer and connecting it to the BBB, I can successfully upload a sketch once - after that I get the "not in sync" error from avrdude and nothing happens on the BBB. If I pull the FTDI cable from the computer and reinsert it, I can upload again, once.
Everything works flawlessly on my Ubuntu Linux system, so I presume that the BBB itself is OK.
I've tried FTDI drivers both from the arduino package and from FTDI's web site. I've tried two different WinXP machines and it happens on both. Pulling the cable from the BBB end and reseating it doesn't do anything, nor does resetting the BBB with its reset switch.
When I am unable to upload, if I pull the cable from the BBB, loop TX back to RX, and type some characters in a terminal, I see them get echoed back. Doing this also clears up whatever keeps uploads from working.
Any suggestions? Running the IDE on my Linux system works for me, but I'd like to be able to work on my main Windows system.