"Are you sure you want to leave this page" prompt when posting

Anytime I post something (such as now) and I click any button on the toolbar (such as bold, align centre, emoticons, etc), I get this infuriating popup from windows saying "Are you sure you want to leave this page? Message from webpage: You have unsaved changes." and it gives me the options "stay on this page" or "leave this page". Clicking "leave this page" lets me do what I want (like bold, italics, etc) but "staying on page" does nothing. Please help. This problem is very anoying and time consuming.