Hmm, ok, I was seeing the exact same rebooting issue. Didn't realize it was an initialization issue on powerup. Just curious, what drivers/programs are you using to control it on ubuntu?
I haven't delved into the Windows drivers but clearly they're doing something that the Ubuntu ones aren't for this issue to exist. I just noticed it's happening after a "cold boot" of the amBX. I'm just calling it an initialization issue because that's what it seems to me. Just wanted to clear that up first just in case the way I was using "initialization" wasn't clear.
I'm using a combination of boblight, ruby-usb and combustd to get it to work. This isn't my blog but I used this as a guideline to get everything up and running:
I'm using a combination of boblight, ruby-usb and combustd to get it to work. This isn't my blog but I used this as a guideline to get everything up and running:
http://slickeel.wordpress.com/2011/03/25/philips-ambx-starte...
The tricky thing was realizing I had to have it "initialize" in Windows before this would work.