Hi Craftysnapper,
just an update on the file size problem. I noticed that some of my Excel spreadsheets wouldn't save, just gave me a "Windows has detected a problem" and asked me if I wanted to send an error report. This I duly did, a couple of days later an upgrade arrived, and surprise, surprise, Elements now works perfectly, as well as my Excel. Looks like it was a Windows corruption somewhere. I'm now happily saving files with lots of layers in them.
cheers,
Jon