Hi, what makes you think it's a virus?
ClamXAV, free Virus scanner...
But first I think you should do this...
Safe Boot, (holding Shift key down at bootup), run Disk Utility in Applications>Utilities, then highlight your drive, click on Repair Permissions, reboot when it completes.
(Safe boot may stay on the gray radian for a long time, let it go, it's trying to repair the Hard Drive.)
No it isn't!
There are many forms of ‘Malware’ that can affect a computer system, of which ‘a virus’ is but one type, ‘trojans’ another. Using the strict definition of a computer virus, no viruses that can attack OS X have so far been detected 'in the wild', i.e. in anything other than laboratory conditions. The same is not true of other forms of malware, such as Trojans. Whilst it is a fairly safe bet that your Mac has NOT been infected by a virus, it may have another security-related problem, but more likely a technical problem unrelated to any malware threat.
You may find this User Tip on Viruses, Trojan Detection and Removal, as well as general Internet Security and Privacy, useful:
The User Tip (which you are welcome to print out and retain for future reference) seeks to offer guidance on the main security threats and how to avoid them.
More useful information can also be found here:
Will it be because the automatic sending of the "bad" email will have stopped?
Hold on a minute, you didn't tell us about that.
Look in your sent mail folder. If you don't see those "bad" emails there then it has nothing to do with your e-mail account. If you do see those e-mails as being sent, then it almost has to have been done by hacking your e-mail account on the ISP server and you need to change your password ASAP. There is no malware known to cause the automatic sending of e-mail from your Mac.
Thank you for sharing your apparent extensive knowledge of Apple products. Your suggestion worked, and looked like repairs were made. My husbands computer was running perfectly all day yesterday and, needless to say, he is thankful I found you and so am I. Isn't there an area here where I can give you "official" kudos so you can get points?