Are you the Moodle admin and are you interested in trying out SEE?
This was a bug which should be fixed in version 0.7.8. Can you please confirm which version you are using?
I am the Moodle administrator, but very new at it. We are offering our first classes starting this week. When the math professor started loading her first test, we realized that we had to have a math editor, so I began looking at the Moodle docs. I found the file there. I downloaded dragmathformoodle_v0.7.7.1, unzipped it on my local machine and uploaded it to the server using ftp. I made the change to adminlib to add the button. When it starts java, it gives me this error. I can click OK and it will load equations, but I shouldn't have this error. I saw the post about having the DragMath directory in common, so I uploaded another copy of the directory there thinking that might be my problem, but it didn't change anything.
you can get 7.7.8 from sourceforge (info is in docs) or you can wait till later in the week and I will repackage zip to address the additional development that Alex has done.
you can also look at their cvs and compare the location of the unfound files with their location in 7.7.1