Can't tell if Hacker, bugs, or exploits

[krytosss 6]

tl;dw -I shoot a guy (mischy), the server says I killed him, but he just stands there for a few mins -I'm hiding out inside the hospital, with dozen+ zombies at the glass, then the guy I killed is alive and walking right past the zombies shooting at me -A zombie makes it inside the building -My ammo suddenly disappeared.

1.7.1.5

Server: JP1

Potential hacker/exploiter -- mischy?

6/21/2012 11pm-12pm PST~ -- I don't have the exact time. I can try to figure it out if it's needed.