I put in a support call with my host and I just got a cheery response.

Unfortunately, your server has already been compromised.  We found WINNT/system32/rdriv.sys.  The rdriv.sys is the Rbot.aja worm.  The only recourse, at this point, is to reload your operating system on a new primary hard drive.

The virus attacks a weakness in the SMTP service in older versions of Mailenable. The search has come to an end and the misbehaving of applications will cease.