Ever since Windows 98, a powerful, but unnecessary and rarely used facility known as DCOM (Distributed Component Object Model) has been an integral part of Windows. The DCOMbobulator checks the effectiveness of Microsoft's security patches and allows the user to increase the security of their system by simply turning DCOM off.
The strange history of DCOM
Many years ago, Microsoft began modularizing Windows and their Windows applications by breaking them into functional components with well-defined, "version safe" interfaces. The idea was to allow pieces of Windows and applications to inter-operate.
The first name given to this effort was "OLE", which stood for Object Linking and Embedding. OLE suffered nearly terminal birthing pains and developed a reputation for being a bad idea. Undaunted, Microsoft renamed it COM for "Component Object Model". This was still the same old OLE, but Microsoft appeared to hope no one would notice. COM fared somewhat better, but it wasn't until Microsoft gave it the sexy name "ActiveX", and built it into virtually everything, that developers finally gave up trying not to use it.
What does all this have to do with you?
Absolutely nothing . . . and that's the point. Somewhere along the bumpy road from OLE through COM to ActiveX, Microsoft's industry competitors began working on a distributed object system called CORBA. Microsoft's object system was not distributed, but as we know, if anyone else has one, Microsoft does too. So Microsoft looked around and quickly stuck a "D" (for Distributed) in front of COM to create their Distributed Component Object Model — DCOM. Then they crammed it into every version of Windows from Win98 on (even though no one needed it, wanted it, or was using it), so that they could say Windows already had a distributed component system built in.
What does DCOM do for you?
Well let's see . . . it attracts Internet worms and permits your system to be remotely compromised by malicious hackers. Other than that, it's of absolutely no use other than for Microsoft's "We have That Too" chart. There may be some custom corporate application developers who managed to make some use for it, but mostly no one ever has. Nonetheless, it's there in Windows so that the competitors' CORBA isn't.