Dear all,
I have solved the problem...
http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/biggrin.gif
I would like to share it with all of you.
1. In DOS shell, change the directory as the following path:
C:\altera\quartus51sp1\bin\cygwin\bin where the mount command exist.
2. run the following commands to specify mount point for the Cygwin toolset
mount <Quartus® II Install directory>\bin\cygwin\ /
mount <Quartus II Install directory>\bin\cygwin\bin /usr/bin
mount <Quartus II Install directory>\bin\cygwin\lib /usr/lib
Be sure that before you can execute the commands above correctly, you should login PC as an administrator.
Thanks all the help...
David