error freeglut

Hello everybody,
I just start with cuda programming. after install the sdk, I went to the directory C, and I tried to compile the examples, all compile whell, but when I tried to run the graphics examples, the next error appear:

freeglut (/home/phantom/NVIDIA_GPU_Computing_SDK/C/bin/linux/release/fluidsGL): ERROR: Internal error in function fgOpenWindow
X Error of failed request: BadWindow (invalid Window parameter)
Major opcode of failed request: 4 (X_DestroyWindow)
Resource id in failed request: 0x0
Serial number of failed request: 30
Current serial number in output stream: 33

and that kind of error is for any graphic program I try to run. I already installed the opengl librarys.
I wish someone could help me. its very important for me.
Thank you.

Sounds like you are trying to render this on a non-NVIDIA gpu. The SDK examples which use OpenGL expect to run and render on the same GPU.