Worms/Viruses/Trojans    
Packed.Generic.306 Fri, Jul 16 2010
Severity 
Aliases: ,Trojan.Sasfis [Symantec],VirusDoctor [Symantec],Viruses [Symantec],W32.Koobface [Symantec]
Infects: [Windows 2000, Windows 95, Windows 98, Windows Me, Windows NT, Windows Server 2003, Windows Vista, Windows XP]
Description:
Packed.Generic.306 is a heuristic detection for files that may have been obfuscated or encrypted in order to conceal them from antivirus software.

Impact:
Not Available.

Propagation:
Not Available.

For Further Information:
http://www.symantec.com/norton/security_response/writeup.jsp?docid=2010-071611-0456-99
Solution:
Disable System Restore (Windows Me/XP).
Update the virus definitions of your antivirus product.
Run a full system scan.