The saga continues...

Well so far I haven't done a Windows job and wiped my hard drive.
Following the advice of someone on forums.bsdnexus.com I have used a different command (portinstall) to start reinstalling glib and gtk. There appear to be a lot of dependencies etc for glib and it's recompiling approximately 100 packages ranging from pango to kde (all of kde...)
Needless to say this is taking some time...