There's been a fair few issues with firefox plugins - this is usually down to the plugins themselves though rather than being firefox's fault. Best bet is to check you're using the latest version, and if not use another browser for the time being such as Chrome (never had an issue with that.)
Lot of people here (including me) really aren't the biggest fans of IE... it's got the slowest javascript rendering engine on the planet, doesn't support any significant part of HTML5, is pretty rubbish on the standards compliant front (though they are getting better) and generally speaking there's a lot more security holes with it than any other browsers.