Release Notes for Microsoft Script 5.7
This release of Windows Script brings the improvements in scripting made during the Vista development cycle to downlevel platforms. During any release cycle we test with increasingly effective analysis tools designed to expose stability problems, memory leaks, and potential security weaknesses in code. The results from this testing comprise the vast majority of changes. Of course, we also include all the current security updates. This is the fastest, most robust, and secure release of Windows Script available.
Why Version 5.7?
The primary reason for changing the version number from 5.6 to 5.7 is to simplify servicing and support by synchronizing the versioning to a consistent scheme based on Vista build number. The minor version increase does not indicate significant new features. The scripting feature set is substantially the same as 5.6, with only minor additions.
About the Install Package
We’ve switched from IExpress to Windows Package Installer technology. This provides for more flexible install, uninstall, and easier deployment. For example, this package may be uninstalled through Add/Remove Programs in Control Panel.
For additional information, see Command-line switches for Windows software update packages. 
For detailed technical information and guidance on deploying this type of package, see The Package Installer.
What’s New
In addition to the general improvements noted above, the following are some of the notable changes in this release.
JScript
•	This package includes the improved garbage collector (GC) shipped with Internet Explorer 7 and Vista. The new GC can dramatically improve the performance of applications that create large numbers of objects, such as Ajax-style web applications. These performance improvements are now available to users of earlier browsers.
This work replaces and improves upon KB919237. If you have implemented KB919237, we recommend removing the registry keys.
•	New progid JScript.Compact implements the JScript Compact Profile (ECMA 327). This is a profile of the ECMAScript language standard with a subset of features. See the ECMA 327 standard for more information.
•	Update for new Daylight Savings Time rules.
VBScript
•	VBScript defines a new global function GetUILanguage that returns the current default user interface language. This is the same value returned by the Windows API GetUserDefaultUILanguage. Script authors can now write code that is aware of the current user’s language preference.
•	Fix crash when calling VBScript class objects from JScript.
•	Fix problems with comparisons to NaN in some versions (KB901104).
VBScript and JScript
•	Support for large address space on machines with > 2GB RAM (KB890048)
•	Improved stack checking makes script more robust in the face of stack overflows.
•	Fix miscellaneous TLS leaks and memory leaks, including using the RegEx object with more than 10 sub-matches.
Windows Scripting Host
•	Fixed rare deadlocks in remote scripting. Prevents occasional hangs in remote scripts.
•	Fixed propagation of error return codes in remote scripting. Error codes produced by remote scripts are more reliably returned to the client.
•	Fixed attempting to load nonexistent wshenu.dll which created performance problem in login scripts.
Included KB’s
This release also contains fixes described in the following knowledgebase articles.
KB831191
KB834742
KB836863
KB890048
KB892296
KB901104
KB903648
KB906092
KB917344
KB919237 (superceded by new GC)
KB925753
KB933811
KB933812
KB933873
KB940284