Here is a download link to it.
If it detects version 4.26.0.1000 or an older version installed, it'll uninstall it first before installing the new version.
I've already installed and run a scan and tested it.
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This is the information in the change log:
* Definition server connection enhancements
* Enhanced Vundo detection/removal
* Updated technology to handle the hi-jacked USERINIT.EXE
* Numerous technology additions to the scanning engine to deal with new rootkit infections
* Enhanced Diagnostic Abilities
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