As ALWAYS, it would be helpful if you could provide more information...

And while you're doing that, is abc.exe blocking keystrokes? If you're unsure what this means, consider if you wrote a Perl script using Term::ReadKey (read the docs), and set it to block keys. This could be a problem. What is it? What does it do? Did you or someone you know write it? (This would be some of the "more info"!)

In general, run3 should just work if you're using it correctly. Are you using it correctly? What code are have you written? (Hey! More info! Okay, enough snarking.)

You could also check out Win32::GuiTest, per Corion. OLE works well with objects that respond to OLE commands, but sometimes you just need to use the SendKeys function, which is available in GuiTest.