Dear Manhas, please clear the cache, browsing history, passwords, restart the system and relogin. Now try to continue from where you left. If you are able to complete it, it is fine. Or else please write to AIIMS Helpdesk at: aiims.pgexams@gmail.com along with the screenshot. Even last year Candidates had to face the same issue and authorities stepped in to let Candidates select the Exam city.