Adware:Adware (or spyware) is a small program that is designed to show advertisements (in various form and degrees of intrusiveness) on your computer. It often reports personal information back to its owners. As a result your sense of privacy can be violated.
It is a known technique that malware, adwares, viruses, keyloggers etc use to hide from users - to drop files on the computer that use the same name as a legitimate file but in a different directory. WinDir.winlogon locates a file winlogon.exe in %WinDir% on your computer. The legitimate winlogon.exe file is located in %SystemDir%. Do not remove %WinDir%winlogon.exe unless you are 100% sure it is a threats.
Technical details (How to remove WinDir.winlogon(pop up))