Thanks for the reply. What constitutes a "removable device"? I've seen posts on other threads which suggest memory could cause this, but I wouldn't classify this as a removable device. Hard disk drives seem to be classified as fixed devices so perhaps it's something else.
In any event, to "disconnect" a device is it sufficient to pull the SATA cable out of the device, or does the cable have to be removed from the motherboard socket?
The problem is due to a bad memory module. After disconnecting all peripherals I still got the problem, but it started to work when I pulled all the memory except one. Gradually inserting more ended up failing with one module. Without it the system works fine, with it, in any slot, I get the b9 code. I guess memory is considered a removable device. I thought memory test was separate, with codes 2X. Anyway I'm back in action.
Now all that's needed is to get a fix for the inability to sleep properly .....