Honestly, it seems like an inside job.
No people used the same user/pass as other sites. My account has 13 failed login attempts on it, because I use unique user/pass combination on every single site.
My guess is that other sites have been hacked and they just try all the user/pass combinations on MPH. I've also been seeing failed login attempts to Suprnova as well.
NEVER use the same user/pass on two different sites ever. Get a password manager like 1password, roboform, or if you have too lastpass.
I just came here to check if anyone else is having this. I am getting a failed login attempt about every 6 hours. I also had my suprnova account locked due to failed attempts. Like you, I use a unique password on each site.