It's something to do with how power is allocated by the USB root hub (not the external hub) to all the connected devices.
Best thing is to use a PCI wireless card rather than a USB one, which will reduce the load on the USB root hub.
As you are replacing the system in a week, it's probably not worth the bother.
Another thing - is the external hub powered from the USB port or by external power? If the former, it may well be contributing to the problem.
SD