Bizzare happenings on my blog

Weird things have been happening on my blog. As I haven’t even had time to tinker around with it, it obviously wasn’t my doing 😛
Firstly, [Strangeknight](http://strangeknight.wordpress.com/) told me that my blog was down. I checked, and it was. My web host told me they were restarting the server. But Strangeknight also told me he was unable to post comments anymore. I tested it out myself and got a ‘file not found’ message indicating that my mt-comments.cgi file was missing!
This sounded more serious, because it is not a file that you would accidentally delete. Worse, I knew I did not touch the system which means someone else had done something.
I logged in via FTP and verified that my mt-comments.cgi file was missing. Someone had added a ‘.bak’ extension to it, so I removed it and things seem to be working fine. You can post a comment…
But I really have to get to the bottom of this, because nobody else should have access to my system except the web host, and if they had changed anything they should tell me first! Especially a file so important for enabling conversations on my blog.
Update: The web host says they didn’t touch my files, and suggested I change my password, which I have just done. Quite disturbing … who would hack in and modify my files?