Run a script after a period of inactivity.

I have a public workstation which is used for internet browsing certain web sites.  People use the workstation, navigate to what they need and then leave.  Normally when they leave the browser is not at the regular homepage.  When the PC starts I have IE set to run automatically and the homepage set.  When the homepage is displayed it is inviting to people passing by, by what is displayed on the screen (the homepage) they understand what the workstation is intended for.  After someone uses the workstation and the browser is left at something other than the homepage there is no longer any evidence of what the pc is intended for.  What I would like to do is this.  Is there a way to trigger a script to run after a period of inactivity?  I would assume that after 10 minutes the user is no longer at the workstation and I will shutdown IE if it is open and then restart IE.  This way IE will display the inviting homepage.  Any help will be appreciated.  Thanks!