On Thursday 3.12. 2009 avast! had a bad false positive issue. At around 00:15 AM GMT we released VPS update 091203-0 which started flagging hundreds of innocent files as a 'Win32:Delf-MZG' Trojan (or, in less common cases, as 'Win32:Zbot-MKK'). Among the files affected were high-profile programs produced by Adobe, Realtek, sound card drivers, various media players etc.

On Thursday 3.12. 2009 at 5:50 AM GMT, another VPS update 091203-1 was released, fixing the issue (for both 'Win32:Delf-MZG' and 'Win32:Zbot-MKK'). If you're still using the bad VPS 091203-0 we recommend to invoke a VPS update immediately. To restore false positive files from avast! Virus Chest please follow the instruction in the following article:

Restoring false positive file from Virus Chest

Those who have not used their computers between 00:15 AM GMT and 5:50 AM GMT will most likely not be affected.

We deeply apologize for any inconvenience this has caused.

ALWIL Software

avast! Home Edition 4.x
avast! Professional Edition 4.x

avast! Server Edition 4.x
avast! Small Business Server Edition 4.x

Operating systems:

Microsoft Windows NT 4.0 Workstation
Microsoft Windows 95
Microsoft Windows 98
Microsoft Windows ME
Microsoft Windows 2000 Professional
Microsoft Windows XP Home / Professional / Media Center Edition
Microsoft Windows Vista Home Basic / Home Premium / Business / Enterprise / Ultimate
Microsoft Windows 7 Home Basic / Home Premium / Professional / Enterprise / Ultimate

Microsoft Windows NT 4.0 Server (Any Server Edition)
Microsoft Windows 2000 Server (Any Server Edition, incl. Small Business Server)
Microsoft Windows Server 2003 (Any Server Edition, incl. Small Business Server)
Microsoft Windows Server 2008 (Any Server Edition, incl. Small Business Server)