If the pages work fine on other machines, then the problem is in that machine. Also, I just visited the Mint website, and it seemed to be working okay.
Try starting the browser(s) from the command line, then clicking on the dysfunctional functions. It's long shot, perhaps some useful error messages will be thrown to the terminal.
You might also use journalctl
check the logs for the most recent entries after doing the testing.
Just out of curiosity, have you tried a CLI browser, such as lynx, links, or w3m?