Black screen

[fsidegrind]

here is the config:
server (uvnc runs as service, no mslogon, just password, no screensaver with password protection)
workstation (xppro service pack 2, uvnc viewer)

problem:
when I connet to server from workstation (this is over WAN), i am able to login, but all i see is a black screen.

notes:
there is not a screen saver with a password on the server machine.
When I try to connect with RDC all i see is a blue screen and mouse, but am able to log on.
I am able to connect to server (with vnc and rdc) from many other workstations (over WAN) with no problems


Any ideas?