Network Problem. pls help!

i am running windows 7 ultimate in macbook air bootcamp.
i was able to connect to the internet with no problems until a few days ago. but my desktop pc has no problem connecting to the network. however my laptop connects to the network automaticaly after 5 mins if its kept near the router (Blekin N+ model:F5D8235UK4).
there are no new firmware update for the router or the network drive in my laptop.
and there are no obstructions that restricts wifi signals.
i havnt installed any software that conflicts with the driver.
everything used to work flawlessly before.
it is the same with my iphone. therefore i am guessing its router problem.
but the network is shown in list when scanned. but connecting to it from more than 5 meter off it seems to be the problem.


would some please help me solve this problem?
any help/replies will be appreciated.
thank you.