I've got a microsoft usb mouse that functions per normal until I plug in a Huawei 3g dongle. Then the mouse stops functioning and the 3g dongle connects successfully.
I have tried un-installing all usb drivers and it automatically reinstalls it at startup. Mouse functions again until I plug in the 3g USB device again. I have also tried plugging in USB memory stick and that doesnt cause conflict so it seems that the issue is only relevant to the 3g modem.