Same happened me before. Ring Ros helpdesk on 1890 201 106. I would be fairly sure it is still on the computer it has just been moved to a different folder or file location. Ask them for the name of the file (I can't remember the file name offhand but can check on monday if needed) and the folder where it should be. Do a search on the computer. When you find the file, put it in the correct folder and this should sort it. ROS is just set up to automatically find the cert in a certain location on the computer and if the cert moves it will not work.