Established site occasionally redirecting to install.php

We’ve had the site youngadulthollywood.com has been established and running for since July 2013. It’s running WP 3.8.1 on a shared hosting from ipower.

Recently several of the content contributors have been reporting that they will occasionally get redirected to install.php.

I’ve checked the .htaccess file, and everything seems to be normal there. I also checked the database as suggested here, and everything checks out OK. Nothing was changed in config.php

The problem seems to be intermittent. The authors will get redirected to install.php for a few minutes regardless of where they navigate within the site, then everything will go back to normal. Below is what the author described. (They initially thought the install.php was a password-reset prompt, hence the reference to “the prompt”. All reference to such may be interpreted as the “install.php”).

I was initially writing the post title, and in the main body of the post is where the password prompt appeared. The last time I received the prompt, I was inserting a photo into the post.

When I tried going to the main home page, I got the same prompt, only this time it was the whole screen, and not inside of what I was working on. (If that makes sense.)

So, I exited out of that tab and when I navigated back to the site, the prompt was gone.

Any help that can be offered would be greatly appreciated.