I'm not seeing it
It sounds like one of those tools that changes key words into links in order to gain advertising revenue.
Does it only happen here?
Have you allowed any browser toolbars to be installed lately?
If it were something new on the board software, which hasn't changed recently, then everyone would see it.
That's why I asked about browser toolbars. That's another way to get that "feature" but it would be specific to you and that browser.
There are many free plugins that add in a toolbar install. They ask your permission, but it's way too easy to click through the defaults and unintentionally allow the toolbar install.