You cannot install Office Communicator Web Access Plug-in in Windows Vista, in Windows 7 and in Windows Server 2008 R2

You have a client computer that is running Windows Vista, Windows 7 or Windows Server 2008 R2. You log on to the client computer as Administrator or you run the computer in an elevated mode. In this situation, when you try to install Microsoft Office Communicator Web Access Plug-in, you receive the following error message:

Important This article contains information about how to modify the registry. Make sure that you back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base: To resolve this problem in Windows 7 and in Windows Server 2008 R2, install the following update:To resolve this problem in Windows Vista, use one of the following methods:

Method 1

Enable User Account Control and then install Office Communicator Web Access Plug-in.

Method 2

Remove the "Always install with elevated privileges" Group Policy. To do this, follow these steps:

1. Start Registry Editor. To do this, click Start
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   , type regedit in the Start Search box, and then press ENTER.
   
   
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   If you are prompted for an administrator password or for confirmation, type the password, or provide confirmation.
2. Locate and then click the following registry subkey:
   HKEY_CURRENT_USER\Software\Policies\Microsoft\Windows\Installer
3. Right-click the AlwaysInstallElevated registry entry, and then click Delete.
4. Locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\Installer
5. Right-click the AlwaysInstallElevated registry entry, and then click Delete.
6. Exit Registry Editor.

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.