When I have my plasma TV on AND my laptop connected to the power supply some of the Xanura units rear the units have problems (sometime they do not respond)
When only the plasma is on, OR the laptop (connected to power suply) I do not have this problem.
The plasma allready had a plug, but as test I also added a plug to the laptops power supply.
Guess what... No more problems at all with any of the Xanura units when both the plasma en laptop / power suply are on

I guess that the plug's do have somekind of filter in it.