Equation Editor & Mathtype conflict

As a new user I have two questions regarding the installation and functionality of the Equation Editor. Here is the installation problem:On the laptop at my work there appears to be a conflict between the Trivantis Equation Editor provided with Lectora and a previous installation of MathType from Design Science. I have already tried to remove all traces of MathType from the computer (by uninstall as well as scanning with RegEdit in the Windows registry), but this does not help.The symptom of the problem is that when I create an equation and save it to a Lectora page, I cannot reopen the equation. I get an error message telling me that Lectora cannot find the Trivans equation editor, and that I should reinstall Lectora. Reinstallation does not change the problem, however. I have looked at the list of editors under preferences, but unfortunately the Equation Editor is not listed here, so I cannot provide the link manually.Any suggestions about what I should do (other than reformatting the hard disk!!)? Where is the conflicting information about MathType located? Should I have a copy of the free MathType player installed or not?