Last week for some reason my USB MIDI keyboards have stopped working. I have 3 (M-Audio Ozone, M-Audio Prokeys88, Akai LPK25, though not all plugged in at the same time). According to the device manager the drivers are installed and working, but whenever I go to use a device in a program I get an error saying it is 'in use', although no other music program is open. Tried uninstalling & reinstalling drivers to no success. I have another partition I use solely for playing live and everything works fine there, so it's not the hardware / cables. I can't do a system restore because it wasn't turned on. Any suggestions what this might be, or if there is a way to 'reset' the MIDI for Win 7 64-bit?