Not sure how to check for a running application in Mac OS 9 using AppleScript

[celebi23]

Ok, a liitle backstory: I've got the game Mighty Mike (a.k.a Power Pete) set up to launch when my installation of Mac OS 9.0.4 launches in SheepShaver. I then want a script (also in the start up items folder) to check if Mighty Mike is running & if it isn't, it then tells Finder to shut down. Here's what I have so far:

tell application "Finder"
   if exists (some process whose name contains "Mighty Mike™") then
       beep
   else
       tell application "Finder"
           shut down
       end tell
   end if
end tell

If I launch the script in the AppleScript editor & run it & then quit the editor, SheepShaver shuts down/quits as expected. But, if the script is in the Start Up Items folder & I quit Mighty Mike, the Script Editor just adds on blank lines to the beginning of the script. Any help would be greatly appreciated.