I'm using avast! 4.8 home edition. XP, SP2. It's up to date -- I always run the updates when the update alert pops up.
I got an e-mail from Comcast (my ISP) telling me that they have determined that my computer is sending out spam. They put a block on my account (which blocked a couple of my e-mail accounts from sending mail) and suggested that I check for viruses.
I usually run a complete system scan once a week. A week or so ago, it turned up a Trojan in the System Volume Info folder (in a restore point) on my external backup drive, and with the help of forum members here, I deleted it (I've scanned that folder a couple times since then to make sure). Previous scans occasionally turned up other viruses or malware (usually in e-mail attachments I had not opened), and those were all deleted.
I got Comcast to unblock my account, but how can I find out if someone/something is really using my computer to send out spam? In the past few weeks, I have received hundreds of bounced e-mail messages -- someone is obviously sending out spam spoofing my e-mail address as the sender, so the undeliverable messages bounce back to me. I asked Comcast if that's what triggered their e-mail to me, but the Comcast guy said their system doesn't specify which e-mails were suspicious -- it just specifies the IP address of the sender. (They didn't give me the IP address -- I suppose I could try to get it from them and see if it matches my router address or whatever.)
Anyway, I'm not sure what to do at this point, and Comcast wasn't much help. I just want to make sure the spam is NOT coming from my computer. FWIW, I do have a wireless router with WEP encryption. If that's not secure enough, I suppose I could replace it. The wireless doesn't work very well in my house, anyway. Walls are too thick.
Oh, and one other thing -- the e-mail address that was getting all of the bounced-back spams is NOT one of the addresses Comcast was blocking. I have several e-mail accounts with several different hosts. Two accounts were blocked, but I was able to get one to work (by call the host's tech support and fiddling with the alternate port settings). Comcast had to unblock before I could use the other account.
TIA.