VNC Session disappears... help!

[janice.c1.pierce@verizon.com]

Please, I hope someone can shed some light on this...

When I try to connect to my work PC from my home laptop(Windows XP), 
I start the VNC viewer, and input my work IP address.
The password block comes up, and I enter the password.
Then, the session screen opens, but after a split
second it disappears. No message, no nothing. 
- I can connect with this laptop to my work machine when
    I'm directly connected to my work network.
- I can connect from home to other PCs on the work network.

Can anyone help me? 
Thanks
        Jan