clwandling,
Sorry to hear you are running into this issue. Could you answer below queries –
1. What is your OS and version?
2. What is the MyEclipse update site you have used?
3. Did you try to install on Eclipse classic? If yes, which version?
Alternately, you can install using archived update site, here is the FAQ – https://www.genuitec.com/forums/topic/installation-install-myeclipse-using-archived-update-site/