Computer "loses" connection to wireless router intermittently
Solution 1:
This indicates a problem with the drivers of the wireless network device on the computer. Try to reinstall the driver from your computer. If it is Windows Vista/7, your best bet is to uninstall the drivers and let Microsoft detect it. If it doesn't find any, be sure to have the original driversetup at hand.
Try method 1 described here: http://www.petri.co.il/removing-old-drivers-from-vista-and-windows7.htm
if the problem still continues after reinstalling the drivers, try another USB-port in your computer.