Ok, here's my try at this:
First of all disable all bridges, delete them what ever.
Secondly look at this thread:
http://www.tfproject.org/tfp/showthread.php?t=87904 I had the same problem and I solved it by buying an antenna extension. We could use some more info i.e. OS and also what are your routers and nics? 802.11b or g?