problem: connected, but not connected to a wireless network

Hi, I am not new to computers, however I am new to networking. I have
managed to setup a home wireless network with internet and printer/file
sharing capabilities about four times previously. Here is my setup:

Windows 2000 Pro with MN-500 wireless base station software. The connection
from the gateway/router is wired.

Windows XP Pro with Belkin USB wireless adapter.

I reinstalled windows xp and now have to connect it back up to the home
network. Here is my problem. I get a shared internet connection, no problem,
but I can not access the MSHOME network. It is not just files and printers,
but I cannot access the MSHOME network at all, even though I have a shared
internet connection. It tells me though that I am connected to it. Every now
and then I will get it working correctly and do not know how I did it and
then after some time passes it will change. I dont know if the configuration
changes or what, but the icons in the network connections changes. I have
checked the following things already:

Both computers belong to the same workgroup, MSHOME.
Both computers are using the same channel.
The WEP security key is accurate.
I can access the internet from both computers.
The Base Management Utility (from going to http:// 192.168.2.1) detects
that my computer is connected to the network.
I have disabled my antivirus and firewall software along with the
windows firewall.
I have tried rebooting.
I have installed the driver, USB adapter, and software included in, I
think, every possible configuration.

Please help me. If more info is needed just let me know. Thanks.