The 'Countdown to Christmas' at the top of every MMC page is run by a Java applet.
I've found that FF3 is better at Java than FF2, so if you're still on FF2 upgrade and see if that helps. If you're on FF3 you could try turning off Java. Go to Tools/Options (Firefox/Prefs on a mac) and in the 'content' tab there should be a Java tick box.
MarthaK, what version of IE are you using? There does seem to be a bug with some versions of JVM clashing with IE! Have a look at:
Just running ccleaner would be a good idea anyway!!!
I use the Camino browser on the mac for using MMC and have turned off Java and the pages load a lot quicker!