glxgears and system freeze

[metin]

Hi,
Whenever I run glxgears my system freezes. The mouse cursor can be moved 
  at first but then it freezes too and my system completely freezes. 
Only hard reset solves the freeze.

My system specifications: amd 2500, nvidia 6800XT, 1gb ram

Status:          Enabled
Driver:          AGPGART
AGP Rate:        8x
Fast Writes:     Enabled (when disabled, the same problem persists)
SBA:             Enabled

"glxinfo | grep render" gives the following:

direct rendering: Yes
OpenGL renderer string: GeForce 6800 XT/AGP/SSE/3DNOW!
     GL_NVX_conditional_render, GL_SGIS_generate_mipmap, 
GL_SGIS_texture_lod,

Any help would be much appreciated.