I am also having a similar issue. I've got the first revision of the hardware. I have tried changing channels on the router, but still get the wireless dropping connection under heavy load.
I know it isn't my ISP because machines connected through ethernet stay up and connected (no interruptions), just wireless machines.
We do have cordless phones, but I'm sorry, just having cordless phones in the house should not keep me from using a wireless-N router. Besides, I've tried different channels with no luck.
D-Link has to have a solution to this.