Cannot connect to my Windows Exchange server in wifi

[Joop_Siroop]

Since 3 days my Outlook cannot connect anymore to my Windows Exchange server.
The situation always worked fine.

Exchange is on a NT server which is connected to a 3com Wifi/gateway/router by cable.
Two other PC's are connected by Wifi and working fine
I can Ping my NT server from the other machines
I can ping my other machines from the NT server
I can acces the internet in a browser on all machines

Using Real VNC I can control my Wifi PC's from my NT server
I cannot connect to my NT server using VNC viewer on the other machines (yes service is running on the NT machine)

I have BlackIce (firewall) running for about 2 weeks. When examining the problem today I exited blackIce and Outlook was able to receive some messages from Exchange. But then it stopped again and OUtlook says it cannot connect to the Exchange server.

Anyone an Idea?
Thanx in advance for your help.

[Restek]

[icecube]

On your system logging on, you need to set NetBIOS over TCP?IP
Rt click local area connection -->properties--> select internet protocol TCP/IP
click "properties," click "advance," and select the WINS tab.
Click 'enable netbios over tci/ip'

Windows XP and 2000 use DNS instead of NetBIOS to name domains As a result, if you've installed only TCP/IP on the XP or WIN2K client, and if you've disabled NetBios over TCP/IP, the client can't join an NT 4.0 domain