It’s actually a desktop my dad put together for me. My OS is running on a SSD while my videos and music are stored on a mechanical drive.
Pretty sure there wasn’t any AV installed beforehand on it, and the reformat was somewhere around September last year.
Installed Avast 6 and malwarebytes at that time after the format and haven’t had any problems with the updates til the recent one yesterday.
No worries then, just have to keep an eye on it and see how it goes 
I have the same problem with Avast 7.0.1426 and Windows 7/64 Enterprise (error event on Base Filtering Engine, Windows Firewall and very slow start up)
I installed it just 2 days ago, none other virus or anti spyware software is active.
I could bring the machine back in working state by disabling all real-time shields except for the File System Shield.
You say none is active but is there any installed?
Everything seems fine at the moment. This is the first bootup after i shut down the computer yesterday night. Will report if problem surfaces again.
Only application software is installed, see the list below.
Adobe Acrobat 9 Pro - English, Français, Deutsch Adobe Systems 3/7/2012 9.0.0
Adobe Flash Player 11 ActiveX 64-bit Adobe Systems Incorporated 3/4/2012 6.00 MB 11.1.102.63
Adobe Flash Player 11 Plugin 64-bit Adobe Systems Incorporated 3/4/2012 6.00 MB 11.1.102.63
Adobe Reader X (10.1.2) Adobe Systems Incorporated 3/4/2012 116.1 MB 10.1.2
avast! Free Antivirus AVAST Software 3/6/2012 7.0.1426.0
CCleaner Piriform 3/4/2012 3.16
CDBurnerXP CDBurnerXP 3/4/2012 17.2 MB 4.4.0.2971
Crystal Reports Basic for Visual Studio 2008 Business Objects 3/4/2012 173.2 MB 10.5.0.0
Crystal Reports Basic Runtime for Visual Studio 2008 (x64) Business Objects 3/4/2012 64.6 MB 10.5.0.0
DioOrigin 3/4/2012
Dropbox Dropbox, Inc. 3/4/2012 1.2.52
EAGLE 6.1.0 CadSoft Computer GmbH 3/4/2012 6.1.0
Google Chrome Google Inc. 3/5/2012 17.0.963.78
Intel(R) Control Center Intel Corporation 3/5/2012 1.2.1.1007
Intel(R) Management Engine Components Intel Corporation 3/5/2012 7.0.0.1118
Intel(R) Processor Graphics Intel Corporation 3/5/2012 8.15.10.2418
Intel(R) Rapid Storage Technology Intel Corporation 3/5/2012 10.6.0.1002
Maple 15 (32-bit) Maplesoft 3/7/2012 15.0.0.0
MATLAB R2012a (32-bit) The MathWorks, Inc. 3/4/2012 7.14
McAfee Security Scan Plus McAfee, Inc. 3/4/2012 8.30 MB 2.0.181.2
Microsoft .NET Compact Framework 2.0 SP2 Microsoft Corporation 3/4/2012 93.2 MB 2.0.7045
Microsoft .NET Compact Framework 3.5 Microsoft Corporation 3/4/2012 81.5 MB 3.5.7283
Microsoft .NET Framework 4 Client Profile Microsoft Corporation 3/5/2012 38.8 MB 4.0.30319
Microsoft Device Emulator (64 bit) version 3.0 - ENU Microsoft Corporation 3/4/2012 2.30 MB 9.0.21022
Microsoft Document Explorer 2008 Microsoft Corporation 3/4/2012
Microsoft Office Professional Plus 2010 Microsoft Corporation 3/5/2012 14.0.6029.1000
Microsoft SQL Server 2005 Microsoft Corporation 3/4/2012
Microsoft SQL Server Compact 3.5 Design Tools ENU Microsoft Corporation 3/4/2012 8.41 MB 3.5.5386.0
Microsoft SQL Server Compact 3.5 ENU Microsoft Corporation 3/4/2012 0.30 MB 3.5.5386.0
Microsoft SQL Server Compact 3.5 for Devices ENU Microsoft Corporation 3/4/2012 46.0 MB 3.5.5386.0
Microsoft SQL Server Database Publishing Wizard 1.2 Microsoft Corporation 3/4/2012 6.19 MB 1.2.0.0
Microsoft SQL Server Native Client Microsoft Corporation 3/4/2012 5.84 MB 9.00.5000.00
Microsoft SQL Server Setup Support Files (English) Microsoft Corporation 3/4/2012 24.5 MB 9.00.5000.00
Microsoft SQL Server VSS Writer Microsoft Corporation 3/4/2012 1.10 MB 9.00.5000.00
Microsoft Visual C++ 2005 Redistributable Microsoft Corporation 3/4/2012 0.29 MB 8.0.56336
Microsoft Visual C++ 2008 Redistributable - x86 9.0.30729.4148 Microsoft Corporation 3/5/2012 0.57 MB 9.0.30729.4148
Microsoft Visual C++ 2008 Redistributable - x86 9.0.30729.6161 Microsoft Corporation 3/6/2012 0.59 MB 9.0.30729.6161
Microsoft Visual Studio 2008 Professional Edition - ENU Microsoft Corporation 3/4/2012
Microsoft Visual Studio 2008 Remote Debugger - ENU Microsoft Corporation 3/4/2012
Microsoft Visual Studio Web Authoring Component Microsoft Corporation 3/4/2012 12.0.4518.1066
Microsoft Windows SDK for Visual Studio 2008 .NET Framework Tools Microsoft 3/4/2012 19.2 MB 3.5.21022
Microsoft Windows SDK for Visual Studio 2008 Headers and Libraries Microsoft Corporation 3/4/2012 115.0 MB 6.1.5288.17011
Microsoft Windows SDK for Visual Studio 2008 SDK Reference Assemblies and IntelliSense Microsoft Corporation 3/4/2012 6.65 MB 6.1.5288.17011
Microsoft Windows SDK for Visual Studio 2008 Tools Microsoft Corporation 3/4/2012 15.6 MB 6.1.5288.17011
Microsoft Windows SDK for Visual Studio 2008 Win32 Tools Microsoft Corporation 3/4/2012 18.6 MB 6.1.5288.17011
Mozilla Firefox 10.0.2 (x86 en-US) Mozilla 3/4/2012 36.0 MB 10.0.2
Mozilla Thunderbird 10.0.2 (x86 en-US) Mozilla 3/4/2012 37.8 MB 10.0.2
MSDN Library for Visual Studio 2008 - ENU Microsoft 3/4/2012 9.0
MySQL Connector/ODBC 5.1 Oracle Corporation 3/6/2012 11.1 MB 5.1.10
Notepad++ 3/5/2012 5.9.8
ON_OFF Charge B11.0110.1 GIGABYTE 3/4/2012 1.00.0001
Origin7 3/4/2012
Python 2.7.2 Python Software Foundation 3/6/2012 51.2 MB 2.7.2150
Realtek Ethernet Controller Driver Realtek 3/4/2012 7.45.516.2011
Realtek High Definition Audio Driver Realtek Semiconductor Corp. 3/4/2012 6.0.1.6387
Visual Studio .NET Prerequisites - English Microsoft Corporation 3/4/2012 2.25 MB 9.0.21022
Visual Studio 2005 Tools for Office Second Edition Runtime Microsoft Corporation 3/4/2012
Visual Studio Tools for the Office system 3.0 Runtime Microsoft Corporation 3/4/2012
Windows Mobile 5.0 SDK R2 for Pocket PC Microsoft Corporation 3/4/2012 128.9 MB 5.00.1700.5.14343.06
Windows Mobile 5.0 SDK R2 for Smartphone Microsoft Corporation 3/4/2012 78.5 MB 5.00.1700.5.14343.06
Windows XP Mode Microsoft Corporation 3/6/2012 1,161 MB 1.3.7600.16423
Okay, i just booted up the system and the problem came back again. It went away upon reboot.
Any idea what i should do now?
Can you schedule a Boot Time Scan with Avast? I wonder if there is some activity that is intermittent in the boot sectors that is coming and going? Upon reporting the problem goes away upon reboot but than returns, there might be some issue here. Turn on the PUP activation under settings, just so that we can assess what is going on. Make sure that Windows Defender is off.
Report back the results of the scan when you can.
Jack
PS. Could this user submit a memory dump to Avast after the Boot Scan has completed?
I don’t have any resolution, but I have the same issue basically. Windows7 update of avast today caused my OS to hang after reboot, after entering password.
Safe Mode - boots.
Safe Mode w/Networking - hangs after password.
Removed avast via the removal tool and now OS boots fine. There is an issue with Windows7 and the latest Avast update, as my XP system functioned fine with the latest update.
Pardon my foolishness, how do I create a memory dump? And where do i submit it >__<
Just did a boot time scan, nothing was detected except for a few corrupted RAR archives. I’ll attach the scan log.
Same problem here. Avast wanted to update the program and I did so. After reboot, the desktop never would show. Hung on the Welcome screen. Went into safe mode and uninstalled Avast and all worked fine. Went to Avast site and downloaded latest Pro version and installed. It booted to desktop but the PC was slow, especially on the Internet. Windows Firewall could not start either. I’m leaving uninstalled until this bug gets fixed. Running Windows 7 Home Premium 64 bit.
UPDATE: I used the aswclear utility from Avast and reinstalled latest version of Pro Avast. All seems to work ok now. Fingers crossed.