Why Can't I Type in the Search Box for this Forum?

I keep having a recurring issue were I'm not able to type in the Search box at the top of this forum. The box highlights and my cursor is blinking, but the text I type is still in the grey italics prompt text and not an entry in the Search. When I click the Search button it acts as though I haven't typed in the box. I can't get it to accept my entry no matter what I do.

 

How do I get around this?