Vista - Will Connect Won't Connect.

Ok first of all here is the equipment i am using. I have a Wireless router a Belkin N1 Vision and on my desktop i have a N1 Wireless desktop card and the PC is running Vista.

The problem.
I have set up my secure network and it all connected fine. then all of a sudden while i am just browsing the net the status on the bottom right corner says not connected, no matter what i do it will not connect, even tho the passkey has not and did not change.
An added feature with the Belkin Router is that u can enable a Guest network. So i enable this secure guest network and its connects and i can work away. but then i try to change back to the original network and it still won't connect.
One thing i have noticed is when i was connected to the original network i was connected at 300Mbps, and now i am looking at the connection of the guest network and its 54Mbps. I turn off my pc off and when i start it again it connected fine with the guest network then all of a sudden, it disconnects. and now it will not connect to either nework. i have no idea if this has anything to do with it? If anyone has ANY suggestions on how i can get back on to the original network i would applicate it. I have a windows XP laptop and this can go on the original network with no issues!!!!!

Many thanks

Kevin