A quick google search yielded an interesting hit. Although not exactly your issue, it does involve your router and some Sony hardware trying to connect wireless. It involves using a static setup on a PS3, while including the uPnP options that like to automatically do that setup. Check it out here.
There's also a thread on Sony's site that seems to be your issue, fairly exactly, though a different router. A firmware update on the router seemed to fix their issue. Check it out here.
One way or another, you're just having a conflict somewhere with settings between the two devices.
If you don't have a bunch of custom configuration on the router, I'd recommend first updating the firmware, and then restore to factory defaults. See if you have the issue with a clean slate.