V delphi AssignFile pouziva tzv "current directory", mozes si ho skusit nacitat na zaciatku programu, http://www.delphibasics.co.uk/RTL.asp?Name=GetCurre ntDir,
alebo zistit si hockedy cestu k tvojmu exe, ExtractFilePath(Paramstr(0)), a nastavit si current directory http://www.delphibasics.co.uk/RTL.asp?Name=SetCurre ntDir