Bump: My girlfriend has a Kyocera Zio ($10 cricket black friday sale POS).. It doesn't disable the router when it connects, but it does cause issues endeniably.
If another wireless device is already connected: that device gets "kicked". My EVO 4G for instance will be disconnected from the network when she first connects. But the network is still avaiable, I just have to click back into it from my phone.
If nothing else is connected wirelessly: Her phone cycles back and forth between connected and disconnected from the WAN (Wireless Area Network).. I have to reset the phone or completely disable WiFi, and then set my device up to get "kicked" to get hers to stay connected.
So it doesn't affect my router, but clearly there are WiFi issues caused by some phones. I don't really know how to help yours, but maybe someone will read this and find our common denominator to help with your issue.
-Edited to add color, draw attention to specific line.
Edited by dragonsdontfly, 24 March 2012 - 01:26 PM.