BTW,
If you access the members area you should at least have access to the security patch for v7.5.6.
Your current version. 7.5.6pl on the right side of the screen
At least it is something better than what you have for now.
Yeah, but anything under v7.5.8 is declared "insecure", the patch for 7.5.6 simply secures them to that build's reported exploits, not the ones discovered after the post date.
If the config file is hosed it could be just an error with the script that wiped the file (rarely happens) so it could be that you weren't hacked; do your error logs show any errors other than that one you posted?