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Symantec system center clients shows red exclamation mark.

Created: 17 Jan 2008 • Updated: 02 Mar 2009
Hi all...
I am new to symantec administration...
Now i am facing a problem. In symantec system console the 4 remote clients connected shows status as "threat found" no other description is found. What is that.? ho can i get rid of that.
Then on another 10 clients a red exclamation mark is there. but no description. what does that indicate. virus definitions are up to date.
whether this is something to which i should immediately act or whether these are warning messages.
please help me out as early as possible.