If this is a Windows box, you can easily download wget and write a small script to parse the output from that command in perl or python.
Run the script as a scheduled job every 5 minutes.
If the app is down, run an "iisreset" command.
If it's Linux/UNIX, you may need to download wget (esp. if you run HP-UX or Solaris), and then write a small script that checks the error status, and if it fails, run an "apachectl restart" or whatever command your webserver needs to restart.
That should help you out

. There's even VbScript to do this on the Internet if you look closely enough.
Thanks,
Mitch