Frank,
This might be a case of a known GPC problem that causes a stack overflow if the loop runs very often. If it's that, than the crash should occur sooner or later depending on the stack limit set.
A work-around in this case could be to assign the loop condition (substr(zeile2,1,ls)=suchstr) to a Boolean variable and test this in the `until'. Thanks a lot! The program seems to work now...
Stephan -- ---------------------------------------------------------------------- Stephan Eickschen Tel. : +49 (0)8153 28-1351 GeoForschungsZentrum Potsdam (GFZ) Fax. : +49 (0)8153 28-1207 Division 1, Section 1.2 c/o email: eicksch@gfz-potsdam.de DLR Oberpfaffenhofen www : http://op.gfz-potsdam.de Box 1116 82234 Wessling Germany ----------------------------------------------------------------------