In english:
Invalid signature, valid examples include:
OpenOffice 3.1 on Windows Vista / NeoOffice 2.2.3 with MacOS 10.4 / OpenOffice 2.4 on Ubuntu 9.04
In french:
Signature invalide, quelques exemples corrects :
OpenOffice 2.4 sous Windows XP / NeoOffice 2.2.3 sous MacOS 10.4 / OpenOffice 2.3 sous Ubuntu Gutsy
These versions are all obsolete.
Maybe an update with newer will be fine.