OpenGL.error in USRP2

Hi,

    I am getting the following error after installing GNU radio package
for usrp2 in my machine.

OpenGL.error.Error: Attempt to retrieve context when no valid context

I am having Quad Core Q9650 3.0GHz, with Nvidia Quadro NVS 295 graphics
card installed in Ubuntu 9.04 (32bit)

THANKS
MADAN