Site reverting to install.php

My site keeps reverting to the WordPress install page whenever I try to login or just visit the homepage.

I’ve been able to successfully login and do some work, but within a few minutes it goes back to the install page.

The website is https://uhclthesignal.com/wordpress and it’s running the 3.5.1 version, which was installed the day it came out – haven’t had any problems until now. Also, this isn’t a new install, the site has been running since 2009.

I’ve check the database and all of the tables are ok, and the install.php file is in the wp-admin file. I even repaired the wp-options table, but it keeps reverting to the install page.

Any help with this would be greatly appreciated.