This post probably only applies if you have the above laptop model.
My newly installed version of MT4 (from IG) just wouldn't work. It froze my laptop leaving it completely unresponsive, the only option was to do a hard boot.
After a few hours on the internet I found another soul with the same problem - and thankfully the answer.
I've updated that post there. Please see http://www.forexfactory.com/showthread.php?p=8025178