Problem following links in Messenger conversations

Hi,
A friend of mine is having this problem after messing around with some security settings. She can´t follow any internet links posted in a messenger conversation window. Nothing happens when she clicks on them. Everywhere else, in emails, on webpages etc, links work as usual, but in messenger it might as well be “regular” text. She can´t remember what options she turned on or off when she was “adjusting” the security settings, and I can´t find anything that should work like this…

Anyone had similar problems who can give me a hint what has gone wrong here..?