1. You have a mismatch between the C version of the Glib, and the Perl module. Get the latest of both if you can. Or, get old versions that match. That can be tricky, because to get gtk2 going, you need matching levels of glib,pango,atk,and gtk2. There have been quite a few releases over the past few years.

2. There has been some discussion on the gtk2-perl maillist, in the past couple of days, about Mandrake patching their Perl in ways that break things, if you don't stick with their distro's modules. The consensus on the maillist is Mandrake is not a good platform to do gtk2-perl on. The maillist is at gtk-perl-maillist