Hi Yogesh and S Sriram
Thank you both for your help!!
Yogesh i have marked your last response as the correct answer as your advice has helped me find the solution.
I found that all i needed to do was to delete the C:\Users\{username}\AppData\Local\EPMOfficeClient folder, and then re-open the Analysis for Microsoft Excel straight after and then try the Log On button and the EPMOfficeClient folder recreated itself and the Log On box appeared!!!
Knew there had to be a easier way then a full NT User Profile recreation!!! User has tested and he is very happy - so am i!!!!
Thank you guys!!!!!!