There are two designers that ship with MyEclipse, and you can’t open the source editor unless you open one of them. It sounds like the classic designer has always worked for you and the new designer barfs. If you go into the file associations again, find JSP, select “MyEclipse ‘Classic’ JSP Editor, hit “Default” then OK, then restart your workbench using the -clean command line argument, then close all your editors and try and open a JSP page, does it still try and use the new designer?