Simple script no longer works on Lion
===

I have a simple Applescript that takes a number of images in a folder that you select and then mirror images the images using Graphic Converter. This script will run if I place it in a new AS file; however, if I try to run it a second time I get the following error "Can't get window 1 of application "GraphicConverter". Invalid index." 

This script always ran on OSX 10.6

I'm running OSX 10.7.4 and Graphic Converter 8.1 (latest version).

Here is the script

    tell application "Finder"
       activate
       set loopFinish1 to 0
       set pathName to (choose folder with prompt "Choose Folder Containing Images")
       set fileList1 to every file of folder pathName
       set loopFinish1 to count of items of fileList1
    end tell
    
    tell application "GraphicConverter"
       activate
       repeat with i from 1 to loopFinish1
           set currentFile to item i of fileList1
           open currentFile as alias
           mirror window 1 in horizontal
           close window 1 saving yes
       end repeat
    end tell
    
This is driving me crazy!