Have you checked the access to the location of the folder, it allows you to check read / write 

Go to set up Tab in repositories / options / repositories  then look at File Store Path and click the Check Accessibility box. 

Another option go to tools / system tools / rebuild repository

Hi Howat_Nexus, thanks for the advice, greatly appreciated. I have already tried this but the rebuild repository option is greyed out and cannot be selected?

What about the check accessibility in the first option also check the path mirrors others.  Have they previously been able to see this? Are they connect to the internet etc? How about licences how many do you have and are other people in at the same time?