I tried as you suggested. No network activation, and ONLY activated/installed on the main domain.
I'm on a linux / hostgator VPS with CGI ...
This is a multisite with about 15 subdomains...
The error logs show nothing useful to me... any thing else I can look into or provide you with?
I had it uninstalled, but can reactivate for you if you think it would be useful.
EDIT: and I commented out the Options -Indexes as suggested
I have it turned on right now, and I'm looking at the logs... it appears that curl is showing a 500 error and downforeveryoneorjustme.com is showing a 403...
but I am getting legitmate 200's, 404's and 301's in the mix, so I think that maybe it's something with the way that curl and similar programs are calling?
I know that my own script that checks is showing that it's down, but I'm able to access the site ( I assumed this was an admin user privilege )