Problem with wireless

Hi,

I stay in an apartment and hence we have a lot of wireless networks from my neighbors..
The problem I am facing is particularly with one of my neighbor's wireless.
* When their router is on my laptop and mobile does not connect to my wireless network.
* if I am already connected the connection drops. Then I have to connect to their network.
* this problem occurs only when I am in the living room it doesn't happen if I am in any other room as they are farther from neighbors house.
* I don't face this problem with any other networks

Infact my phone and sony vaio laptop hangs and I have no choice but switch off my router if I have to use internet

Could any one please tell me what the problem could be

Thanks/..