I've had a similar problem with ME, but then I've got dozens of apps on the machine and often run over a dozen of them at the same time so am not surprised when the puter freezes. I may be stating the obvious but one cause was simply running out of space on my hard drive. Something else that seemed to slow down the computer was if I had a large number of files in the recycle bin, or a dodgy USB connection or CD drive, or lots of temp internet files.