Quote - thanks nruddock! That worked but as expected all my face morphs are lost. So I have to start over because this file was pretty much only a custom face. My question before I start again would be: Does this V4-Poser incompability mean that I cannot use custom morphs on V4 at all or are only certain morphs affected by this?

So long as you save with binary morphs turned off, things will be fine.
(see this thread for the technical details of the source of the problem -> http://www.renderosity.com/mod/forumpro/showthread.php?thread_id=2679897)