CrunchBang Linux

Hi there,
In short, my wifi lasts for a few secs (15-20secs) and will timeout shortly after. As long as the PC is on LAN wire, everything runs smoothly. If however I unplug the LAN cable, open say a youtube video then (say 20secs later) the quality degrades and connection timesout. Someone pointed out that it might be a certificate issue. what do you think? Any help would be appreciated. What sort of commands do you want me to reproduce to make things easier for you? I would also welcome a brief explanation so as to get a better understanding of what's going on behind the scenes.
FYI
I am as newby as it gets - linux AND crunchbang. This is my very first and serious attempt to steer clear from Windows and so far I have managed to sort most of my issues with help available online. However, I am still unable to use the wifi.
Cheers