The way I read it, I don't think he's experiencing droppage, I think the problem is that he can't connect at all. (???)
Basically, if you are having problems with encryption like alex_2017 mentions in his original post, try removing encryption temporarily on the wifi router to make it open. Then try to connect to it. If you can connect then try using WEP encryption. If that works, but WPA encryption does not, your card doesn't support WPA encryption so you'll have to use WEP if you want to continue using that wifi card in your PC. If you can't connect even on an OPEN ssid, I don't think the drivers for the card are working. Many older cards do not have WPA encryption support since it is a newer protocol than WEP.
Thank you! I will try it without encryption.
Not much hope though ... Because the card had been working perfectly under windows with the same router and same settings.