A program that ran correctly under Windows 2000 (and older Windows) behaves strangely under Windows XP Professional. The program was compiled with Delphi 7, and calls DLLs that were compiled with C++Builder Command Line Tools 5.5. In some Win XP systems (but not in others), just when the program is invoked an exception error is issued sometimes, and the program stops; I have to try several times and finally the program runs correctly. Should I recompile the program in an XP system? Other programs I compiled in Win 2000 run correctly in XP. How can I check whether there is a conflict in some (old) DLL that is used by Delphi? Thanks for your help.