Segmentation fault when using "gpu::PyrLKOpticalFlow::dense"

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I am using OpenCV-2.4.3 on Ubuntu 11.10. When I run the demo algorithm "pyrlk_optical_flow_gpu" provided in the sample, I get a segmentation error!! It seems that this error is in the function "PyrLKOpticalFlow::dense"

Did any one experienced the same problem?? Is it a bug in that release of OpenCV or am I doing something wrong? Any help or feedback will be very appreciated.

Thanks