My web host provider uses suPHP and I'm having a lot of trouble installing a php script correctly. Even something as simple as <?php phpinfo(); ?> seems to give me an internal server error. Does anyone know how to fix this problem?

1) Make sure no files directories are chmod 777, they should be 755 instead.
2) Make sure your .htaccess file contains no php-related directives. They should be declared in a php.ini file in your root website directory.
3) Make sure the script you're running is under your user account / group's permissions and not root.

If you follow what Mike says you will be all fine, even something as simple as <?php phpinfo(); ?> will work like a charm. suPHP is not a bad thing at all, but due the nature of the configuration you will need to have your setup more secure, hence the 755 instead of 777 permissions.

All of my folders are chmod 755 and all of my files are chmod 644. My .htaccess file is completely blank. (0 kb)

In that case i would contact your host to find out what is wrong, you can also try to look if there is an error_log in your directory and/or look in the error logs of apache (if using cpanel you can do this from the control-panel).

The fastest solution would be contacting your host directly, that is, if they offer you 24x7 support :)

I’ll try to contact my web hosting provider but I doubt they will respond. Thanks anyways.

It should be an easy task for them to fix, and response times should never be longer as 30minutes to a hour.

Good luck with solving your issue.

For some reason it works when I upload it to the domains folder (I'm using Direct Admin) and then move it to public_html.

Hooray!