n5050 wireless shut down problem

hi,

i have a dell inspiron n5050. i bought it 2 months ago.  when i bought it i could connect to any wireless i wanted. 2 or 3 weeks later i restored the system to previus date because i had installed a couple of games which when i unistalled, i noticed that my computer was toooo slow.. after that when i try to connect to ONE specific network my laptop crashes the router and whoever is connected to it gets off. i don't have this problem with any other wireless. i have contacted the internet service and we fegured out it isn't a router problem.. by the way (and i don;t know if this is of any significance) this ONE specific network is the first network i entered when i restored my system. i run win7. for any more details ask..

thnx