Pretty Permalinks cause site to crash on main domain

Do look at the .htaccess file and check the RewriteBase. It should be commented out or read:

RewriteBase /

It sounds like it might be written as:

RewriteBase /xyz

Where xyz is the name of the folder controlling your subdomain.

Also, what happens when you hit save twice on the Permalinks page?

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)