I am wondering whether the fact I recently plugged in an old Epson GT7000 scanner may have something to do with this. I recall ages ago I had to download a driver for it as the old CD had gone missing or was for 2000 (can't remember). This time I was prompted to find a driver for the Twain 32 or something like this which was duly found in the hard drive and there was a warning that things could go wrong on the install screen and maybe they have.
Does anyone have any suggestions? Is there a simple way to go back to default USB settings? Thanks.