I've got a PNP running with Shinken 2.0

I've noticed that, when time changes, or by force, or by synchronization,

All PNP graphs comes down.

It seems that NPCD can't write perfdata when the time had change.
PNP Web interface is still ok, just those perfdata files which aren't updated anymore.

Logs aren't saying anything interresting,
even in NPCD, pnp, nagios, shinken or syslog.

The only slightly related log I've found, it's nagios deamon (combined with NPCD) saw the time change and adapt itself...