Hello,
i bought un new computer two days ago with windows vista premium and i installed bitdefender antivirus plus v10 today.
i have launch a deep scan and BD found a backdoor "Backdoor.Bifrose.ADR" in the file "wextract.exe" in the system32 directory.
this file seem to be included with vista.
Is there a method ton control if the file is infected or not ?
Thanks 
Vladim
P.S: i'm french thus excuse me if my english is not good 