VB Script to keep pc from locking...(For the corp PC users)

Here is a quick script that I wrote to keep from  Office Communicator from setting me to the away status while I am sitting at my desk doing other things. It will pop a box and if you hit the OK button it will terminate the script. If not after 4 minutes it will hit alt,tab to switch the screens...
 
 
Here is the code:
 
Option Explicit
Dim objShell
Set objShell = CreateObject("WScript.Shell")
Dim counter
Dim returnvalue

Do
   returnvalue = objShell.Popup ("Click OK to Canel Script",240, "Screen")
   If returnvalue = 1 then
   Set objShell = Nothing
   wscript.Quit
   End If
   If returnvalue <> 1 then
   objShell.SendKeys "%+{TAB}"
   End If

Loop