Problem with Copy Paste Behavior

[wanglichunpost]

Hi there,
 I'm using Emacs 21.4.1 on Debian
After using C-w or M-w,I find myself unable to use the copying/pasting
features with other apps. After i copied some text in other apps,click
the middle button of the mouse in emacs,it always paste the content of
the kill-ring,just the very text C-w or M-w done.
I could not figure out yet if or how I could configure the behavior
wanted. Any hints would be appreciated.

Regards,