I have a MBP and I'm not sure if there's something wrong with the USB port on the left side. I plugged in the USB receiver from the VX Revolution mouse and it did not work. Didn't know if I had to install software or something but I then plugged the receiver into the USB port on the right side and it worked fine. I tried putting the receiver into the left port again and it still did not work. However, if I plug a USB flashdrive into the port, it works fine. Any ideas of why some devices would work and others don't? TIA!