Installing and enabling module causes 500 server error/access issues

I installed and enabled Google Analytics on my live site (Drupal 5.10)
All seemed to be well, it appeared in my modules and I was off to input my tracking number in the UI.
I added the number, looked at the default settings which seemed to be fine, and hit "save configuration".

At this point, things got scary. I received this 500 error message:
Forbidden

You don't have permission to access /index.php on this server.

Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.
Apache/2.2.9 (Unix) mod_ssl/2.2.9 OpenSSL/0.9.8g DAV/2 mod_auth_passthrough/2.1 mod_bwlimited/1.4 FrontPage/5.0.2.2635 Server at meredithcutler.com Port 80

Worse, this message then appeared every time I tried to access anything in the admin menu!

So, I used the back button (firefox) to get somewhere in admin where I could fix the situation. In my status report, before I disabled and uninstalled the module - I received an error message indicating that "google analytics needs to be configured". But trying to configure just sets off the chain of 500 errors.

Is there something I need to change in my setup before installing this module? I didn't see anything in documentation and don't want to break my admin priviledges.