execute the installer on windows server 2008(rc0)
it claims
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EmEditor Professional(English) Files in Use
The following applications are using files which the installer must update. You can either close the applications and click “Try Again”, or click “Continue” so that the installer continues the installation, and replaces these files when your system restarts.
the application(s) is windows explorer.
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every beta version on windows server 2008(rc0) claims this.