MS Remote Desktop Connection Won't connect

Microsoft Remote Desktop suddenly stopped working. I've been connecting find with this app for a long time. Now I can't get a connection to any host.

1. I fired up VPC and I was able to connect to the host via Windows with no problems.
2. I used another Mac and I was able to connect to the host.

Here is the message RDC give me:
You have been disconnected from the remote computer.
The remote session was disconnected because no Terminal Server client access license are available for this computer. Please contact the server administrator.

Here is what I've tried to do. None of this has worked.
1. I repaired permissions.
2. I deleted preferences.
3. I removed all related files of RDC and reinstalled.
4. I repaired permissions once again.

Any other ideas?

 

I'm connecting to a Windows Server. It's a server on campus that I can run .NET on.

 

In lab we've had the whole class logged on to the server. That's about 40 students. And I can get into via other RDC right now. There was a problem last week, and a registry hack was given to all students. My Mac seemed to still work without any modification. I logged on multiple times after the problem occurred. Now I can't.

 

No. Because as I said, I can open VPC and use RDC from there.