I had a F900BT installed in my 2007 Jetta in late september 2008.
About 2 weeks ago the endless reboot cycle started.
The dealer told me that I would have to let them send it to Pioneer for repair.
Instead I tried deleting the 4 files detailed earlier in this thread with immediate success. 5 days later, still no problem.
Many thanks to vegaslaptop for that timely post!