When connected to DVI out, networking becomes slow.

When I connect my MBP to my Fujitsu P42XHA58 plasma screen, all networking grinds to a halt. It takes minutes to load google.com for example. Other services fail such a local network access. As soon as I disconnect the DVI cable, networking is back up to full speed. I have only tried wi-fi as my switch is in another room. I have tried switching from 802.11n to b, no encryption, WEP or WPA, all still have the same problem.