I have software on the server that looks for and gets rid of malware and virus's. It regularly scans all mail, and Webspace and FTP Space on the whole server. The only thing that I can think of is maybe you might be seeing ads that "play" automatically. You should never see pop up ads, but sometimes the stupid ads will play sound automatically. When I catch one doing so I get the url and block it in the Ads Software I run to help pay for the site, so no-one will ever see it again. The latest one was Charmin that I blocked. I hate ads that auto start with sound. But that's it. This server is clean.