This is more than just a little annoying, it is a major flaw in Firefox 4 and a serious backwards compatibility issue.

I will be recommending my clients and users not to take upgrades Firefox 4 until it is solved. Let me explain why:

My application like most applications needs to interact with the user repeatedly on every page as it validates their entries. It may well go back and forward several times via AJAX calls to the server until they eventually complete the form successfully. If they click Prevent this page from creating additional dialogues, then my legitimate error and confirm messages will be suppressed. They will think that nothing is happening. They will blame my application, phone my customer's help desk and eventually the call(s) will land up with me tearing my hair out.

Please fix ASAP!

I'm having the same problems as scottka.

Does anyone know how to undo it if the box has been checked? It must log the page somewhere.

A reload with a cache bypass seems to be sufficient.

Reload a web page and bypass the cache with:

• Press and hold Shift and left-click the Reload button.
• Press "Ctrl + F5" or press "Ctrl + Shift + R" (Windows,Linux)
• Press "Cmd + Shift + R" (MAC)