Product & Category Pages Not Working, Other Pages Ok

All of a sudden this morning I have this issue where all the pages on my site work OK except for the product pages and category pages. So the home page, the "About Us" page, etc. all work fine, but no one can get to my product or category pages because they get the big red "Service Unavailable" notice.

Any idea why this would be?

I've deleted the var/cache folder but that didn't change anything.

Any other troubleshooting steps?

Edit: The same problem is happening in the backend. Whenever I click on an individual product like I was going to edit it, I get the big red Service Unavailable sign.

You may try to fix all your database tables.

You may try to fix all your database tables.

OK, how do I do that?

OK, how do I do that?

You can ask your host to do that for you or use phpmyadmin in cPanel.

You can ask your host to do that for you or use phpmyadmin in cPanel.

OK thanks!

My host ran a repair script on the tables and everything seems OK now. Thanks cscartrocks!

My host ran a repair script on the tables and everything seems OK now. Thanks cscartrocks!

For your information: Service Unavailable page is displayed when some error occurs. You can open the source code of this page (Ctrl+U hotkey) and see the actual error description in the bottom of the page.

Also you can enable the development mode in order to see the errors. Add the following part of code to the end of the config.local.php file:

if ($_SERVER['REMOTE_ADDR'] == 'IP_ADDRESS') {
    define('DEVELOPMENT', true);
    error_reporting(E_ALL);
    ini_set('display_errors', 'On');
}

Replace the IP_ADDRESS with the IP address you use.