Hi
That is a weird one, what i would suggest is forgetting the network on your phone then re-adding it, then test and see if this does the same thing.
If that does not work have a look at your wireless channel, if this is sitting at 11, 12, 13 try lowering that (this should not make a difference as its a new devices but its better to be safe than sorry)
If that fails change the Wireless Authentication Method, your router should be using WPA/PSK and WPA2/PSK, change that to WEP (worth while making a minor chnge in the WiFi networks name so that its easier to re-add the network on your other PCs/Macs without having to forget and then re-add.
Let me know how this goes,
Burkem5