The remote host is running a version of Windows which has a flaw in its RPC interface which may allow an attacker to execute arbitrary code and gain SYSTEM privileges. There is at least one Worm which is currently exploiting this vulnerability. Namely, the MsBlaster worm.

see http://www.microsoft.com/technet/security/bulletin/MS03-026.mspx http://www.microsoft.com/technet/security/bulletin/MS04-012.mspx http://www.microsoft.com/technet/security/bulletin/MS05-012.mspx http://www.microsoft.com/technet/security/bulletin/MS05-051.mspx http://www.microsoft.com/technet/security/bulletin/MS06-018.mspx