killing process after idle time

["Daniel Gall" <gall@epost.de>]

Hi there,

i´m not (yet) too familiar with linux but would like to exchange the os of
several computers in our school from windows xp to linux (knoppix
hd-install).

Beforehand i want to make sure if (and how) i can accomplish that a program
(i.e. Mozilla) will be killed after a certain idle time (no user activity)
and will restart right after.

Background: A pre-defined e-learning info-website should be seen by default
when students start using the computer. Since i am aware that not all
students will remain on that site i want to make sure that this page is
reloaded automatically after, say , 5 minutes of no user activity. 

Thanks a lot for any help,
Daniel