You don't say what you have or have not tried or exactly how these images are popping up. Clamxav focuses on infected files. What did you download recently that might have been infected? Have you gotten rid of it?
Are they popping up in general or only when you use a web browser? If these are popping up in general, have you tried repairing permissions (use Disk Utility found in Utilities Folder), shutting down and re-starting?
What exactly is happening and what did you try to stop them? You make it sound like we all should know, like we've all gotten infected and are familiar with this particular virus, but in the twenty years I've used Macs, I've never gotten a virus (knock wood). So I don't know what you're talking about and I can't help you unless you make clear exactly what is happening when and what you've tried to put an end to it.
It seems like you are another "MAC Defender" victim, this is how you got it:
Most probably you were using a search engine and clicked on a link. This piece of malware has been spreading via poisoned search engine links
According to a macworld article (New Mac Trojan horse masquerades as virus scanner | Antivirus & Security | MacUser | Macworld) you can remove it using Intego's VirusBarrier Plus and VirusBarrier Express products, available in the Mac App Store.
Sorry, I re-read the article and noticed that I had it wrong, Virus Barrier only detects it but doesn't remove it. These are the instructions for removing it:
- Open Applications > Utilities > Activity Monitor and quit any processes linked to MACDefender.
- Delete MACDefender from the Applications folder.
- Check System Preferences > Accounts > Login Items for suspicious entries.
- Run a Spotlight search for "MACDefender" to check for any associated files that might still be lingering.