Starting this week I have had a strange problem on my network. Some background of my setup:
Internet is provided by a adsl-modem.
A D-link Dir-600 router is hooked up to to adsl-modem.
My computer is hooked up to the router using a cat-5 cable.
My wife's computer is hooked up using a wireless usb dongle, TP-Link TL-WN821N.
Both computers use windows 7 64-bit home premium.
Up until this week everything was normal, we could for instance play Dungeons & Dragons Online together without any network issues. Now every time I start DDO or any other network game, for instance L4D, the whole wireless network drops. I have confirmed that it's not just her computer using an Samsung Galaxy Spica android phone.
Shutting down the game on my end restores the wireless connection automagicly.
My wife can start DDO without the net dropping but if I plug in a wireless network card in my computer and start up the game the connection drops.

So it seems like something my computer, and my computer only, does when starting a game makes the wireless connection write a sad note and kill it self but for the life of me I can't figure out what that might be. I could hook her computer up using cat-5 but I would prefer not to do that.
Does anyone have any suggestions as to what the problem might be, what I can do to fix it or what I should do to get more data regarding what is happening?