[Zope] language environment changes after a while

Hi, I have detected a problem I can't find rational: I integrated PublisherProfile product from cvs.zope.org and after zope starts it writes the time values with formating value %.3f as dotted values of 0.789 . After a while the format changes to comma values 0,789 . Where should I search for a bug ? I don't thing that it is a problem of PublisherProfile product. Regards, Dirk