I do not get a blank page with that link (to page 7 of a thread). Are you sure all users have this issue and it isn't just your logged in user?
I would check your error_logs (if you don't know where they are, ask your host) at the time you get the problem to see if this is a php issue.
Here is a page from the manual about troubleshooting blank or 'white' pages:
https://www.vbulletin.com/docs/html/blank_pages