Comtrend Powerline Ethernet Adaptors

I recently bought a pair of Comtrend Powerline Ethernet Adaptors (with filter) to connect to xbox live. I have an attic bedroom and the modem is on the bottom floor.
When I first got them, around a month ago, they worked perfectly. However over the past week or so they just aren't connecting.
There are 3lights:
-AP/STBY - solid green light
-Ethernet - flickering green / red light
-Status - red light

Any help would be greatly appreciated as my Modern Warfare 2 is screaming to be played online.

Thanks for any help
Tom