I just tried to log on to admin and found a blank screen with just the word: "Resolver"
 
I then tried my main site user page (index.html) and found the same.
I uploaded the file and the screen changed to:
Block 'greeting_block' doesn't exists.
 
I am overwriting my entire site with original files as I cannot afford to be down. I have made a copy of the index.html and will look at this as soon as the replacement files are completed.
 
Is this unique to me and does anyone know anything about it?

For reference I am using 3.3.1

We have been hacked before and via a script we'd never thought of people would find. But they do find everything.
 
First I'd suggest you update to 3.3.2 + all patches.
 
Secondly, check server logs at the date/time of the file upload. That will allow you to see via what way the file got there. Your provider can provide the Apache logs.
 
Thirdly, change the main FTP password and delete any FTP access accounts you don't need anymore.
 
Fourthly make sure you have the correct php.ini settings for safe_mode (on) and register_globals (off).
 
Note that it does not have to be Viart through which the hackers got access, it can be any application on your server or brute forcing of your ftp passwords.
 
Cheers!
 
DickS