plugins and scripts

PLEASE HELP!!!! I HAVE A WINDOWS VISTA HOME, LAPTOP AND I'M RUNNING FIREFOX. WHENEVER I AM ON A WEBSITE(DOESN'T MATTER WHICH ONE), I WILL BE SCROLLING RIGHT ALONG AND THEN BAM!!!! LAPTOP FREEZES AND A LONG BOX APPEARS THAT SAYS 1 OF 2 DIFFERENT THINGS;" UNRESPONSIVE PLUGINS OR A SCRIPT HAS STOPPED RUNNING AND DO I WANT TO CONTINUE TO SEE IF IT STOPS OR DO I WANT TO STOP IT?" I NORMALLY STOP IT AND IT WILL UN-FREEZE FOR JUST A LITTLE WHILE AND THEN IT DOES IT AGAIN. SOME DAYS IT NEVER APPEARS!! AND ALSO WHEN I'M STARTING UP THE LAPTOP A SMALL BOX APPEARS WITH A LOUD NOISE AND IT SAYS" CANNOT CREATE SHELL NOTIFICATION." CAN SOMEONE PLEASE HELP ME WITH THIS PROBLEM BEFORE MY LAPTOP TAKES FLYING LESSONS?

What Add-ons are you using in Firefox? Click on the Orange Firefox dropdown at top left then Add-ons. Click on Extensions and see whats there. Try disabling all of them and see if that resolves the problem. If yes then you can enable them a few at a time and test till you find the one causing the problem. I have no extensions installed. Also look under Plugins. The only ones I have Enabled are Adobe Adcrobat Quicktime Shockwave Flash