I'm running Debian Gnu/Linux, with g++ (GCC) 4.0.4 20060507 (prerelease) (Debian 4.0.3-3),
SDL v1.2.9, using a GeForce FX 5500, and the proprietary Nvidia drivers with GLX.  When I run the simple-demo or complex-demo, I get a blank window and nothing seems to happen. If I run the debugger, I can step through, but it seems that the physics are working fine.  It just doesn't seem to output anything to the display.

Has anyone else experienced this problem?

The only clue I seem to have is the following linker warning:
/usr/bin/ld: warning: libstdc++.so.5, needed by /usr/X11R6/lib/libGLU.so, may conflict with libstdc++.so.6