open (daily_fail, '-|', 'report.pl &') or die "unable to start dail +y_failues.pl";

See Proc::Background and Capture::Tiny, esp for win32, and then forward any stderr stuff up to tk as you please

  system("tk.pl") or die "unable to start c:\\tk.pl";

Hmm, tk.pl and C:\tk.pl are different :)