I posted about this a week or so ago but since then I\'ve done some further troubleshooting so I thought it was worth posting again:
I\'m trying to set up PHP debugging
Use the debugger connection preferences to change the port that Komodo listens to from the default value of 9000 to a system provided free port, 8080, or whatever port your remote host or localhost is running.
In the end I ran this past Activestate's tech support on IRC (#Komodo on irc.mozilla.org) who were really helpful. We couldn't work out what the problem was, though, so I ended up uninstalling XAMPP and Komodo, reinstalling both, and then following the instructions in the Komodo docs.