Hi hastafareh and welcome to these forums !
What time are you playing on Common Grounds ? And what is you in game name ? This has been some sort of my "home" for at least 1 year and half, since I've begun to play CSS, and I've never seen you either on the server.
I'm admin there, but i think you must not play there at the same hours as I. I tend to play between 7-10 P.M everyday, and sometimes at noon too.
What's more, you have to know that knowing an admin is not the only solution for you to get rid of hackers, you can also follow this guide :
http://spawnpoint.com/pdf/reportahacker.pdf and help us to ban hackers from the whole sapwnpoint.com community.
I hope this help you and maybe we'll meet on this server some day.
Skydavo