D.exe is a process which is registered as W32/Mytob-GH Trojan. This virus is distributed via the Internet through e-mail and comes in the form of an e-mail message, in the hopes that you open its hostile attachment. The worm has its own SMTP engine which means it gathers E-mails from your local computer and re-distributes itself. In worst cases this worm can allow attackers to access your computer, stealing passwords and personal data. This process is a security risk and should be removed from your system.