Whenever I click on a thread, or like this post a new post, or reply I get a thing that drops down under the menu bar with the claim

Firefox prevented this page from automatically redirecting to another page. Allow

Pressing the Allow button and it goes but nothing happens..

What is happening..

Install chrome

I want the swing arm off me trials bike doing in chrome, thats about it.

I had a problem like this a year or so ago - turns out the virus was in my wireless router
Moral of the story make sure you password protect your router as well