Someone sent me a file

Someone has sent me a file saying it was a photoshop portable or something, so I opened it and nothing came up or anything, I met this guy from CS his name was Lief Heldge, anyway, I thought nothing of it as my Anti-Virus didnt come up, so I went into a server on CS:S and it came up with a box saying fear a sniper or something, and immediately closed it as I think it might be a hack? I went into a VAC secure server (as always) and then it kicked me out. I need immediate help as I don't want to be kicked from all the servers / banned..