I was wrong, it was a hardware problem.
This is an interesting observation and solution. When I bought my new BCF (I already had a a BCR) the USB worked for a short time then failed. Checked it at firend that had been using his for quite a while, Mine was broken, his was fine. He said I could open both to compare, but as mine was brand new I wasn't too keen.
I took it back to the store and they tested it and it failed so they gave me a new one in a box and I happily went home. It worked for about an hour then failed.
Back to the store. "Yep, it is stuffed. I'll let Behringer know. You can have you money back" How about the display model? "OK lets test it. Works OK, its yours." (Great guys at the DJ Warehouse here in Melbourne)
Been good ever since, but I saw a lot of similar problems from other frustrated people.
I thought it was a bad batch or CPUs as my first 2 had similar serial numbers but the demo unit was a lot earlier.
Perhaps this is solution for all those machines. Well done.
All the best
Royce