rgb.txt missing; in VNC and FreeNX: xcolor and TK apps not working.

This might be related to this bug, but is *not* a duplicate: http://bugzilla.ubuntu.com/show_bug.cgi?id=13921

This is in Ubuntu Desktop Intrepid Ibex.

I am trying to run Crossover Office over FreeNX. This is a paravirtualised machine so I have no access to the Xorg console #7. The exact error when trying to run, is:

"cxsetup:error: error initializing Tk: 'this isn't a Tk applicationunknown color name "Black"'. Check the DISPLAY variable (:1000.0) and your access permissions (see xauth or xhost)."

The problem might be that there is no rgb.txt in /etc/X11 or /usr/X11R6/lib/X11. There is a broken symlink in one of those directories, but the file is missing.
No big problem, I just copied the rgb.txt file from a Debian Etch machine to /etc/X11 and /usr/X11R6/lib/X11, but this did not fix the problem (rebooting does not help). I did a lot of searching on the Internet and installed xcolors. However, I can't run xcolors. The output is:

"Warning: Color name "snow" is not defined
xcolors: Not enough room in color map.
To see colors after this, use the -start option to name a starting color.
xcolors: no colors to display"

FYI, snow is the first line in rgb.txt (255 250 250 snow)

I also tried a VNC session instead of a FreeNX session, this made no difference.

I was able to run xcolors (after copying rgb.txt from another machine) and Crossover Office on another physical Ubuntu machine, without using FreeNX or VNC.