I had an issue accessing every page except for admin and my front-page on a GoDaddy WordPress installation recently. I had just used the addon domain feature to point my domain name to a subfolder in my GoDaddy hosting account.
There could be several causes for a server error, but if you can access your admin and front-page like I could, while getting a server error for single posts and pages, then there’s a good chance your’re having issues with your .htaccess file.
The gist of it is, WordPress tries to create a .htaccess file in the root folder of your blog installation when you try to save your permalink setup in settings — and if your permissions are not set up right, that could be an issue. In my case, after I setup permissions correctly(755) on my folders, I was still getting Internal Server Errors, so I compared the .htaccess file WordPress had just created to another .htaccess file from a working instance of WordPress on my hosting account. For some reason the entries looked completely different — still don’t know if it was a version difference in WordPress that was the perpetrator.
In any case, the working version had:
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress
While the non-working version’s entry was:
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /[domain]/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /[domain]/index.php [L]
</IfModule>
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress
I copied the working version’s entry into my non-working version’s root folder and that solved the problem!