Win95, Win98, WinMe, WinVista, Win2k, Windows Server 2008, Windows 7, WinSer2003, WinNT, Windows 8, WinXP
SONAR.Cryptlck!g108 is a heuristic detection that is designed to detect known variants of the Ransom.Cryptolocker family of threats.
Disable System Restore (Windows Me/XP).
Update the virus definitions of your antivirus product.
Run a full system scan.