Vista - xwindows traffic doesn't work when using VS 2005 latest release

i'm using MS VS 2005 latest release (SPx), against multiple versions of vista
(x64, x86), and Windows XP SP#3 - all HOST machines.

i have lots of VM's (35 or so and counting) ... and i've found that all the
software i have loaded on these VM's work fine ... EXCEPT XWINDOWS (i use
multiple xwindows software packages, exceed, reflections-x, etc.).

for whatever reason, when i connect via TELNET/SSH to a unix operating
system, and attempt to initiate any XWINDOWS application (xclock for
instance), the traffic will not flow to/from that Unix machine to my VM.

FYI: i've verified that no other software on the HOST is prohibiting this
traffic - norton, port blockers, windows firewall, etc. ...

IS THERE A SETTING IN VIRTUAL SERVER 2005 THAT I'M MISSING? i truely want
UNRESTRICTED FLOW TO/FROM MY VM ...

thanks much!