Equation Editor & Mathtype conflict

Thanks for responding, Andy.I am using the latest version (2006) of the International Publisher Edition. But the problem is very specific to my computer, not the edition. That is why I am assuming it is a conflict with a previous installation of MathType. I have the demo version of Lectora and the Equation Editor running on a stationary PC, and there I find no problem in reopening the editor. It is only on my laptop which - it appears - have had a previous installation of MathType, which seems to create problems (with editing a saved equation). Perhaps it is one of these problems that cannot be solved in general because it is so specific to the installation history on this laptop. Michael