Hi John, This is Philip again. Are you using the perl "TK" debugger under AIX 5.3? I have run into some issues which I will try to describe. perl -d:ptkdb test.pl (The debugger pops up no problem) However, when I mouse over the TK debugger window the mouse movement coredumps the application. Now, one thing I did notice is that the unix guy who installed TK, downloaded a pre-built version of libpng.a instead of building the one that came with the Perl::Tk 804.028 package? I am just wondering whether this could be the reason for the TK debugger behaving abnormally. Thank you once more for your invaluable help. Regards, Phil