Files randomly dissapear… WordPress hacked… still!!!

Well, I am out of sorts… I need help…

I’ve been dealing with a very weird issue that files RANDOMLY disapear from my site for the past 2 weeks, usual files missing are index.php, wp-config.php, wp-trackback.php, wp-blog-header.php and wp-load.php. Of course some of those if missing will completely bring the site down. After the first incident I reloaded everything and did a backup. I called 1and1 (hosting) and explained the situation but other than putting the files back from me they were of not much help. We even reviewed the ftp logs and no dice. Here’s what I have done so far:
1. Changed ALL the passwords (1and1 account, DB, FTP, admin in WP)
2. Reinstalled WP
3. Changed the salts in wp-config.php
4. Tracked FTP usage
5. Verified .htaccess to have 644 permissions

Over the weekend I noticed that I couldn’t login because I was redirected to a b374k m1n1 1.01 page with interesting links (yes, back to a Turkish Hacking forum – Turk Hack Army)

Well, this morning happened again. It is so annoying I am considering a complete overhaul but I would like NOT do it if I can avoid it.

Please, I need help…