Microsoft has released an update for Windows 7 Beta (Client) and Windows Server 2008 R2 to resolve some issues with non-compatible applications, or as you can read on the Microsoft download page :
Install this update to resolve issues with non-compatible applications for Windows 7 Beta. For complete details of this update, see Knowledge Base Article KB967062. After you install this item, you may have to restart your computer. This update is provided to you and licensed under the Windows 7 Prerelease License Terms.
At this time Knowledge Base Article KB967062 isn’t available, but this will probably be fixed in the near future.
Source : Bink.nu