I have a python program that implements pygtk for GUI.  I have it running successfully on some MAC computers running os 10.6.*, after installing pygtk with macports.  I have just installed pygtk on a mac 10.5.8 system.  When I execute the program I get these errors:

Xlib:  extension "RANDR" missing on display "/tmp/launch-CQ7og4/:0".

and 

ADP_2.1.py: Fatal IO error 35 (Resource temporarily unavailable) on X server /tmp/launch-CQ7og4/:0.

After this second error the program does not continue.  I looked at the /tmp/launch-CQ7og4/ directory and there is only ":0" in there.
On the other Macs that run this program the first Xlib warning always appears but the program still runs seemingly correctly.
Any help would be greatly appreciated.
You need to install X11-2.6.*
X11 errors with pygtk on Mac OS X 10.5.8