Sounds like your computer may be overloaded. If you are on a laptop: Hold down the Ctrl/Alt and Delete (or Del) keys at the same time. When options come up hit Task Manager. See if you have too many items running and they are either taking up too much CPU or too much Disk space (in terms of %).
Close extra tabs and see if any percentages go down. If you have a high suck up energy printer but you are not currently using it (like my Garden always at ready with options sucking the disk and CPU down)... End that task.
Delete all history from all browsers you are using and empty all caches.
Because it sounds like your computer is simply overwhelmed and freezing up.
