Why is spam being sent to some of my contacts, and how do I get rid of it?

Every 10 days or so, my inbox shows I have sent spam to some of my contacts, and about a dozen mailer daemon comes up also. I rarely send anything to anyone, unless it's a news article of interest. What is the solution?Why is spam being sent to some of my contacts, and how do I get rid of it?
Your account got compromised. First change your password. Account help.http://help.yahoo.com/l/us/yahoo/acct/in鈥?/a> for just about anything to do with your account. Then run anti Virus and Anti Spyware. Should be fine then.Why is spam being sent to some of my contacts, and how do I get rid of it?
I have had a similar problem. I have received e-mails from friends who, when I ask if they sent them, they said no. I honestly don't know if there is a way to stop them from happening.

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