Troj/Daonol-Fam is a family of Trojans for the Windows platform.
Members of Troj/Daonol-Fam typically copy themselves to the Root folder and create some of the following files:
Root\(random filename).bat (clean batch file)
System\sysaudio.sys
The file sysaudio.sys is also a member of Troj/Daonol-Fam.
More information can be found at this Sophos page.