try downloading the dll pack again. I have just uploaded the latest version to make sure the public version is the same as the one I am using here.
Also do a search on your system to see if you have extra copies of mwgfx.dll lurking about. Windows will load the first one it finds and if this is too old it won`t have the functions convimx needs. The only copy you should have is in your windowssystem32 folder