Problems at my work!!

We have been having some problems at work with our Small Business Server 2000. We have 2 offices, 1 across the street with 3 computers and the Server and the main office with 6 computers. At the small office they connect to the server via LAN, at the main office we connect to the server using Remote Desktop. At the main office we have 1 Linksys router, 1 Wireless Linksys Router and a 16 port switch. All the Computers are using Windows XP Home or Professional. The main office is where the problems are at, all the computers can connect to the Remote Desktop except for 2, however they can connect to the internet via wireless. The 2 computers that cant connect give this error:

Remote Desktop Disconnected

The Client could not establish a connection to the remote computer.

The most likely causes for this are:
1)Remote Connections might not be enabled at the Remote Computer.
2)The Maximum number of connections was exceeded at the remote computer.
3)A network error occured while establishing the connection.

Now I have already tried some things, I tried both Wireless and Direct Wire connection with no luck. I installed all the Networking Windows Components and all the Settings seem to be normal.

I also tried using the Business Server 2000 32-bit client setup disks, but that didn’t work. We also have a problem at the main office which I am unsure if it is related where the connection goes up and down about 10-20 times a day and it will either start working on its own or if I reset the Switch or Router. Someone mentioned something about the server assigning Certificates of Authentication and to many of them being assigned?

Any help is greatly appreciated let me know if more information is needed.

Look at Event viewer on the server(will show there if it's a licensing issue) and on the affected computers. I'd suspect connectivity or licensing to be the problem(I assume you've already tried different accounts)