Same issue here, spent all Tuesday, about 20 hours trying to clean the mess up Dr. Web created.
I could not leave my server unprotected so I installed ClamWin but had to upgrade MailEnable in order for Plesk to recongnize it, so now I have spent more money on my server than I had planed to, first Dr.Web's license and now ME Pro license...
I am really upset!
BTW, I had to shut down Dr.Web (disebled it) from Windows services as it kept coming back every hour.
If you decide to install ClamWin make sure you set up a task to restart it every hour as there is something in Plesk that suddenly stops it, I have not found what it makes it stop but in the meanwhile I set the task to reset it every hour.
Hope this helps
Saludos!