windows.html definition, relationships, removal:

This is a part of a malicious parasite that violates user privacy and damages the compromised system. The windows.html file can be used for different purposes depending on the related parasite's type, functionality and carried payload. Although windows.html may not take any malicious actions by itself, it ensures that a parasite is working properly and therefore needs to be removed. DO NOT open, execute or edit windows.html!
The windows.html file is installed and used by Prosiak.
In some cases a presence of windows.html does not mean that your system is infected. The file may actually belong to some fully legitimate applications and therefore must stay intact. If you are in doubt, please scan the windows.html file using you regular spyware remover or antivirus program.