Hi Mike, I think that one means you are using an old version that only worked on MoI v2 or earlier. Check here for some links to updated versions which should work with v3 now:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4933.2

The underlying UI engine changed from MoI v2 to v3 - most things still work the same but that particular script happened to originally use some functions that were specific to the Internet Explorer engine and needed a slight update to work with the new UI engine in MoI v3.

- Michael