Please help: Cannot cut and paste

[platter]

Hello,

I am unable to copy text from emacs 21 into any other application.  I
can copy text from another application and yank it into emacs, but
when I do a C-y or M-y in emacs and try to paste it in another
application, it doesn't work.  I am running emacs 21 on Gnome under
GNU/Linux.

Anyone who can help, it would be very appreciated as this has plagued
me for months and really hinders my emacsing -- any time I want to
copy text from a file in emacs into another application, I have to
open the file in gedit just to do it.

Thanks in advance,

John