Thanks for the reply and sorry I did not reply sooner (thought the forum would notify me of replies but apparantly not).
I am running Windows 7
Not a problem with SQLyog running, it was closed and no process running in task manager.
Was running as Admin and even tried installing by right click and run as Admin, but same issue.
Eventually installed by turning McAfee off completely.
I am not sure if it is significant but now McAfee is also detecting 9.3.0 as a potential virus when downloading.
Regards
John