You can also download process explorer (http://live.sysinternals.com) procexp.exe. It is a tool from 2 russian developers, who have been acquired by microsoft.
The nice thing about process explorer is that you can use the vizor-icon to point to a visible window and it will give you the process it belongs to. Then you can kill the process(tree). You can also lookup the process info on the web, wich will eventually tell you what the process does.