Game freezes: ExtraData + invalid script number

[Mordeth]

If an ExtraData linedef with an ACS_Execute special refers to a script number that does not exist, it will freeze the game shortly after entering that level. Perhaps some more robust error checking is needed there.

[Altazimuth]

I'll check this out later this evening. Do the activation types affect this?

EDIT: I'm unable to replicate this, see link for the WAD I used to test this. http://s000.tinyupload.com/index.php?file_id=07093871017160748457