I guess your using a Alcatel Speed touch USB modem.....
I would suggest the best way here would be to buy a powered usb hub. This way you should be able to have all devices connected.
If you using a powered hub I would suggest connecting the scanner directly to the USB port on the pc and the rest into the hub.
Failing that the last option would be to buy a 4 port usb card that has more than one processor on it, this would then give 12mbs to each usb socket and stop you getting those errors.