Swapping these two files (as root) corrects the issue
mv /etc/pam.d/gparted ~
mv /etc/security/console.apps/gparted /etc/pam.d/
mv ~/gparted /etc/security/console.apps/
Thanks pags for that. Well, gentlemen... four pages of posts just for these three magic lines... what can I say? job done!
Thanks to all you guys on this issue; Bald Brick, Neal and everybody else, I'm greatly indebted
Just one question... some of you say that you don't use/like GParted, what programme do you like to use that you think's better?
(I'll go and mark the post SOLVED now)