I recently got a PS3 and decided to take advantage of the fact that it can be used to stream movies by making my PC a media server. I've done this in the past with the same router I have now before I sold my old PS3, but not on this PC. I've tried using both Tversity and PS3 Media server, but I don't think the problem lies within the configuration of either of those programs because I am unable to ping the PS3.
This problem only occurs when I am using a wired connection on my pc, attempting to connect to a WLAN connection on the PS3. If I switch to WLAN on my PC I can successfully ping the PS3 and connect to the media server.