Windows 7 - WiDi - Problems getting it installed

Hello

I successfully got WiDi working on a Windows 7 Dell Latitude E6420 laptop, that's the good news.  Sadly I cannot get it running on any other Dell Latitude E6420.  I have tried a multitude of configurations, drivers, sequence of drivers.  I am stuck.

I have run the Intel WiDi Compatibility Tool and I get a green tick for hardware, green tick for drivers, and a yellow tick for software.

I run the WiDi Update Tool and it tells me I need Intel Wireless Display Software version 4.2.29.0, it downloads the software, and fails when attemtping to install with the error.

I have tried installing the update 4.2.29.0 manually and i get the error below:

Any help greatly appreciated.