WNDR3400 dropps internet when HP c4700 is conected

Hello all,
My parents have a WNDR3400 and when i was there last I updated the firmware to the lastest (don't know what the rev was and can't find it becasue I don't live in the same state). But after the upgrade, each time we attach their HP OffceJet C4700 the internet connection is lost on all systems connected. Leave the HP off or the wireless connection off, everything but printing works great. We would like to get the printer back online so they can print wirelessly.

Thanks for any assistance.

Ben