Thread:Project:Support desk/navigation bar and formatting disappears/reply

For deleting pages in bulk, check out Extension:Nuke.

You're losing styling because load.php -- responsible for minifying your JS and CSS -- is producing server errors sometimes. I would look at your apache error log to see if you can see the problem there. You might also try upgrading to at least 1.19 since 1.18 is no longer supported and the problem may be fixed in a newer version of MediaWiki.