can't connect to my own network with my notebook

i have a desktop, laptop and a modem for Vonage phone line, all of
them connected to a netgear 802.11g router. i had already setup my
network and ssid and had no problem for a year. But recently i am
having trouble connectiing to my network from my laptop. Even if i get
connected after sometimes i get disconnected.
recently my college network, which has a 11b instead of g have had a
security upgrade and so i had to use a encryption key to get into my
college network.Is it because of the differnece between two networks
that i am having problem connecting to my home network ?...i would
appriciate if anyone can help.....