[Zope] Date-Problem, perhaps OT

Hi, I have a strange date problem on my SuSE Linux machine running Zope 2.5.1. I guess it is probably system related and not Zope's fault, if so please excuse the OT-post. I noted that the system clock was one day off, so the bobobase_modificationtime was too. At the shell at root I issued date -s yesterday and a test date gave the correct output. I restarted Zope and added an object... from that point on, when a Zope object is created and displayed instantly, the date is correct. On the second and subsequent view of the object, the date again is one day off... Does anyone know why this is and more importantly, how to fix it? Is there a way to correct the creation/modification time/date of a Zope object?? Thanks Jochen