Windows 7: Adobe Flash messing things up

Except it says "[object]" instead of .../.../something.swf

I've had this a couple times now and it ONLY happens when I press the back button on my mouse to go a previous page. The sites I'm trying to access have embedded youtube or dailymotion videos. This isn't for every website though only some. Random Curiosity however definitely does it every time I press the back button.

It locks up firefox for at least 10+ seconds. The biggest problem is that half the time this happens, after the error manages to close and firefox resumes, my keyboard is completely messed up. I cannot type or anything because the keys are remapped to something else. Actually I just think the ALT key is permanently pushed down cause whenever I try to type, the short cuts to File, View, Edit, etc. are pressed. Sometimes it goes away but sometimes I have to reboot to fix the keyboard (tried unplugging).

I tried taking a print screen of the error multiple times but it doesn't work so I googled the image.

I can duplicate the error by visiting a site where this does happen, but pressing the back button before all content on the page has loaded. So if I have a page ~50% loaded and press the back button, it happens. Sometimes pressing OK works, other times it freezes the browser.

Maybe a dumb question, but have you tried reinstalling Adobe Flash? I've had a similar problem once, and when I reinstalled AF it worked like a charm...