why does my computer send e mails on its own when my antivirus says its protected?

Here is what i would do, use a free anti malware program.. the best is free , i use Malwarebyte's Antimalware . Get free here . http://www.malwarebytes.org/mbam.php Good Luck !

It could be a virus or someone may know your password. Someone could also of gotten your contacts list and are forging your email address on the header making it look like it is coming from your computer. Also did you check to see if the messages are actually being sent from your account. Did you click on your sent message button and see if they are there?

This has happened to some friends of mine. It stopped after about 2 weeks and that was 6 months ago.

If you're not current using AVG or Microsoft Security Essentials as your anti-virus program, uninstall w/e you're using now and install one of them. If that doesn't get rid of it, download malwarebytes and scan with that. There is a high chance that the bad program will be eliminated in this fashion.

have a good one

One possibility is that you computer is infected with malware that your virus scanner is unable to detect.

No virus scanner detects all malware. Some virus scanners are better than others though. I personally prefer Microsoft Security Essentials. There are many other good virus scanners though, such as Avast or AVG.

someone probably hacked ur email account yo, change ur password