Bobbie,
If you already have an antivirus program DO NOT download another to use as well as your existing one, you should only have one AV program installed and running on a computer.
As those emails were sent when your PC was shut down and not in use, it could either be
(a) a virus that has accessed your computer and email address book in the past and used the info to send emails addressed from you or,
(b) someone elses computer that has a virus and they have both your email address and those of the people who received the email.
I think it highly unlikely that (a) is the case because EVERYONE in your address book would have received the email, so it narrows it down to someone close to you who has all four addresses in their address book and a contaminated computer. It most probably turns out that everyone in their address book got a spam email allegedly from you but only the ones who know you have replied to you.
To be certain that your computer is clean:
1st thing to do is clear out all your temporary files, tool of choice is ATF Cleaner, it is free and you do not have to install it. Download and instructions
here (Windows XP, 2K, 2003 & Vista ONLY)
* NOTE : If you would like to keep your saved passwords, click No at the prompt.
-- Click on ATF-Cleaner to run it
-- Where it says Select Files To Delete, Check the
Select All Option
-- Click
Empty Selected - >
OK
If you use Firefox browser, do this also:
* Click
Firefox at the top and choose
Select All from the list.
* Click the
Empty Selected button.
Then, please download
MalwareBytes' AntiMalware
* Double-click
mbam-setup.exe and follow the prompts to install the program.
* At the end, be sure a checkmark is placed next to the following:
o Update Malwarebytes' Anti-Malware
o Launch Malwarebytes' Anti-Malware
* Then click
Finish
If an update is found, it will download and install the latest version.
* Once the program has loaded, select > Perform Quick Scan, then click > Scan.
* When the scan is complete, click > OK, then > Show Results to view the results.
* Be sure that everything is checked, and click > Remove Selected.
* When completed, a log will open in Notepad. Save this log to My Documents in case it is needed for reference.
Reboot as required.
dave