I looked around a bit and it seems that this is caused by corrupt files.
You say you have cleared your caches.......both?
Try using Firefox and see what happens. IE can cause some instability.
I know that flash tried to do an automatic update for me to the new version and there are known issues with that. Right click on your friends list and at the bottom of the menu that comes up it will say 'About Adobe flash settings' Click that and see which version you have. If it is 10.1 you should uninstall that and reinstall 10.0. Instructions HERE.
Let me know what happens.