I have used my Airport Express for years at BWV with no problems. Then suddenly last year I had exactly the same issue--wouldn't work with the outlet near the kitchen table but worked fine when connected to the modem under the lamp table in the living room.
We had the same problem at BWV in Aug 2009. After much tech input and snarky remarks about using Apple Express, another tech person actually came to the room and figured out that the wires from the modem to the drop near the kitchen table had been stapled/damaged and not working. He rigged up the "hockey puck" hookup and then noted in his notebook that the renovation include rewiring the room. He also asked us to say something when we checked out in order to cover all the bases.
I have noticed at home that the older model of the Airport Express does not have the same range as the newer model. Our older model barely made it to my DD's room upstairs. We since have replaced it with a newer model, strong signal upstairs and even on the front porch and on the patio.