No Signal Problem After Sleep

I'm running a MN-510 adapter and a MN-700 base station. The adapter is
connected to a Sony Vaio in a downstairs room. The base station is upstairs
connected to the modem. My son's X-box is connected to the base station.
After taking out of sleep mode, 20% of the time the adapter lights remain
off and will not come on unless I unplug it from the Vaio and plug it back
in. If I shut the PC down, I have to unplug and plug in the adapter every
time. Once the lights are on everything works fine. I'm using one of the USB
ports on the back of the computer. Any idea why the USB port is having
problems getting powered up?

Jim