LCD goes black while doing video call

This has happened twice on the same machine with a different motherboard. While on a video call all of a sudden my screen blacks out and I lose contact with the other party. My monitor is still on because I can see the blue light, my pc is still running, but I can't see to do anything so I reset the pc. I noticed that when I went to to use the camera it tell me usb device not recognized. No matter where I plug it into the same except for the usb pci card, it works there. All other stuff except my printer work on those ports. I read some where that win 7 64 bit may have some power distribution problem with USB. I was running the camera off a powered USB hub connected to the PC. I removed a Gigabyte p55 board because it lost on board lan,and it was still under warranty, I replaced it with a Asus Sabertooth 55i. Below are my spec. If this thread makes since could you please reply. Thanks. Bruce

I don't belive there is an update for the USB Drivers, chipset is already running latest drivers. I did a bios update for the Asus sabertooth 55i. I'm using yahoo instant messaging fro video calls and the web cam is logitech also updated to the latest sofware. I did notice that the same port my printer was plugged into and working does not reconize my printer anymore. I can plug in my flash drive and it don't reconize it but I have other stuff it will reconize. Can I uninstall usb from device manager and let it reinstall again to maybe get it working rightr?

Update, I did remove the usb hubs and usb chipset Host controllers from device manager and reloaded them. That got all the usb ports working again. One problem my mouse won't wake up the system anymore I have to use the power button. I have gone into device manager and checked the box for the mouse to wake system up but that still don't work. Later I had another Usb issue not reconizing a usb device plugged in and I removed the controllers again and reloaded the and it is working again. This all sounds like a driver / software issue. I think I will e-mail asus and have them look into it. Thanks