Open Regedit
Right-click on HKLM\Software\Classes
Select Permissions
If you only have EVERYONE - this prevents the dll from being registered.
Add the Admin Group and give full control
Click OK and try the install again
Note: Incorrect use of the Windows Registry Editor can have disastrous results on a server operating system. Great care should be taken when making changes to a Windows Registry. Registry modifications should only be carried-out by persons experienced in the use of the Registry Editor application