Apple released an update for AppleScript for Mac OS X. The new version, 1.8.3, is a maintenance release designed to increase stability. The Software Update Control Panel says:
AppleScript 1.8.3 provides increased stability of scripts and script applications, improved Unicode support for text and runs applications created with the latest version of AppleScript Studio.
You can get the update through the Software Update Control Panel in Mac OS X; the file is 2.8 MB in size. As of this writing, Apple does not seem to have added this update to the support site at Apple.com.