Jason: thats whats been happening then! i was working on my old pc ... which battery is empty .. when i start it up i am hold .. have to go into the bios first .. make it recognize my harddisk, save the settings (which also saves more properties) .. and then it will boot up ok
the date is set back to its start though .. i forgot which date .. but quite some days in the past :)
thanks for finding the cause ... now i can sleep again