Yes, I've had this problem for a week or two now, only when on PPRuNe and only when using a mobile device for browsing, never on the desktop machine. The selected forum page has some sort of instant redirect to a scammy page and brings up a popup window that wont let you do anything apart from clicking on its one button, theres no way I'd do that, and cant even go back to the previously viewed page. Occasionally quickly hitting "back" while the redirect is just starting to happen takes me back to the forum page, but Im almost instantly redirected again to a different scam site and popup that locks up my browser.
Jabberwocky82's solution after forcibly killing the browser instance lets me get my browser functionality back but only until the next time I visit PPRuNe on the mobile browser, then it starts all over again.