Solution
Please Install the Updated Packages.
Insight
The x11-data-xkbdata package distributed with Mandriva Linux 2008 had a different configuration for french keyboards, which prevented the generation of the 'oe' symbol through altgr-o, and a few others.
This update fixes the problem.
Affected
x11-data-xkbdata on Mandriva Linux 2008.0,
Mandriva Linux 2008.0/X86_64