False Positive or Trojan?

Hi

I have just updated and run an Ewido 4.0 scan which has quarantined Trojan.Delf.nl found in C:\WINDOWS\$NtServicePackUninstall$\winlogon.exe.

I wonder if this is a false positive or a real Trojan as I had run Adaware and Spybot prior to Ewido and both said my system was clean. My main concern is that if I leave this file in quarantine then I may not be able to log back on to my pc after shutting down. Sorry to sound dumb but I'm still very much a newbie at understanding the file paths of malware, etc. Many thanks for your help.

 

Closed because of duplicate thread with additional info:
https://www.wilderssecurity.com/showthread.php?t=153129