I have an Wi-Fi problems with my Computer and PS3. I had came across the problem before but I just simply rebooted the router, but after several times of doing so, my computer will not connect. My PS3 manages to connect but gets disconnected after 3-5 minutes.
I also had another problem with my WiFi before. The problem before, I would get disconnected from the WiFi on all of my devices (PC, PS3, iPod, and iPad) for 2 minutes but everything would connect back. My family didn't and doesnt' have this problem. The router is just 10ft away, a straight line to my room.
Check to make certain your router is configured for G band, not N. The N band uses G and N, and the PS3 can only talk on the G. So once it acknowledges, it never gets any thing back, so disconnects and tries again.