Hi there
Just testing Bitlocker ( W8.1 Enterprise version).

If by mistake you've left say a USB stick NOT encrypted in a USB slot and re-boot the PC which as bitlocker encryption enabled - you can get prompted for the BIOS recovery keys -- !!!! so either have those or if you are lucky just switch the machine off, re-move the USB device and re-boot -- if you are lucky it will just ask you for the normal bit locker key you need to enter at boot.

Incidentally you CAN use unencrypted USB devices - but as READ only so you won't be able to copy any data from the USB device to the PC.

I'm only testing this stuff on a WORK PC -- I really don't want to faf around with this on home PC's - however I've mentioned this as it might cause some anxiety if you aren't aware of this little "Feature" at Boot when using Bitlocker.