Your running the same system as me pretty much windows me and geforce 4 mx, make sure you check your mohaa folder and make sure it has the following opengl files, once i put them in my mohaa when i was having problems everything worked fine!
The files to make sure that are in your MOHAA Folder are:
Opengl32.dll
nvopengl.dll
I found the nvopengl in my Geforce folder and just copied and pasted it into my Mohaa folder.