This is a $20 router. The capabilities of this router vs the amount of traffic being passed through it are too great. The ratings for this device on Newegg are through the floor because of issues similar to this. Best advice is to go out and buy something worth using, you'll thank me in the long run.
$50 gets you this: http://www.newegg.com/Product/Product.aspx?Item=N82E16833124385
I have the more powerful version of this router (e3000) and I could not be more satisfied. And I am PICKY (Networking Tech by trade)!
We could go through all of the basic troubleshooting steps but I'm certain that it's just a case of an overwhelmed, cheap router. Hope this helps