Hi, having uninstalled tiger and cfingerd the problem didn't return for some days. So it seems one of them was the culprit. Why a tiger or cfingerd cronjob could lead to a situation where most programs can't start anymore remains a mystery to me.
Thanks to all who helped! Andreas Goesele PS: I hope it's not premature to report the problem solved. As the German saying goes: Man soll den Tag nicht vor dem Abend loben.