can't open d.mon window using 5beta_linux

[Glen Gunsalus]

I'm new to grass, but experienced in UNIX/Linux.   Any pointers for solving
this problem?

RH 6.1, gnome, grass install from  grass5beta5_linuxbin_tar.gz on a 233MHz
IBM thinkpad, 64Mb RAM

Installed without error, grass starts up ok (using spearfish data), 
tcltkgrass starts ok
but I can't get a monitor window to open - either from tcltkgrass or
command line in grass.

>From command line:

'd.mon start=x'  yields: "can not allocate any read/write color cells"
subsequent '^C' yields: "Problem selecting x0. Will try once more"
one more '^C' exits to grass prompt.

from tcltkgrass toolbar:

an attempt to start monitor yields a d.mon window containing
the message "can not allocate any read/write color cells" and prevents any 
other
action from the tcltkgrass toolbar until the d.mon window is dismissed.

---- 
Glen L. Gunsalus, Ph.D.   Telephone: (212) 327-8757 
The Population Council    Facsimile: (212) 327-8839,-7678
1230 York Avenue          E-Mail:    glen at popcbr.rockefeller.edu
New York, NY 10021             G-Gunsalus at popcbr.rockefeller.edu