I'm experiencing a strange problem: it's like if my system is always up to date (although I know it isn't). For example, if I download updated versions of a set of currently installed RPMS, rpm -F to freshen them has no effect. And the update agent always says that there is no update available. I've tried to rebuild my RPM database with rpm --rebuilddb without a success. I must precise that initially, the update agent and rpm -F were working correctly as I regularly updated my system. What can cause this annoyance?