Haven't done much capping over the last week, had lots of USB <Unknown Device> Problems, none of the USB drives I record to could be accessed, drove me nuts! My mouse worked OK in all USB ports but nothing else did!
Searched the web for solutions, found many which didn't work, but finally tried the one which did work for me.
Shutdown the PC, and don't just turn it off, but actually disconnect the power cord from the back and walk away for at least 30mins.
Plug power back in and boot up, and all should be OK with all USB ports now seeing everything with no errors.
Worked a charm, so I am now capping again...