MAC cannot connect to our Windows 2003 shared using AFP !!!

Hello!

After shutdown Windows 2003 Std R2. I'm having a problem with one Mac on my network which cannot connect to our Windows 2003 server shares using AFP instead of SMB.

Mac is running 10.5.7, 10.6.2 and my other Macs can all successfully connect to this share using SMB.

I get the login window and enter the correct credentials but I get the message that either Session from user "username" was timed out and disconnected by the server. The IP address of the Macintosh work stationis in the data.

I know the username and password are correct since I can connect to the server via SMB.

I tried created new share folder and connected folder. This also did work.

I tried connect old shared folder. This also did not work.

I tried stop sharing folder and new shared folder. This also did not work.

I can successfully ping, I can successfully log in with SMB - but not AFP. What is wrong?