Ctrl - s, s key problem

[Yan Xu <yax2@Lehigh.EDU>]

I am new to debian and linux. I installed Debian last week. Now, I have 
a problem. If I press Ctrl - s in a terminal or in Emacs, the s key will 
not reponse anymore no matter how I press it. That's annoying. I have to 
reboot the machine to get the s key to work again. But, I do need Ctrl - 
s, especially when using Emacs to edit something.  Anyone  know how to 
resolve this problem.

Thanks a lot.

Yan