Web Shield seems to be corrupting downloads - Avast free 5.1.889

[hake]

Sorry I spoke.  I made a mistake.

[hake]

I have most reluctantly replaced Avast with AVG.  I don't enjoy using AVG but it works so I have no choice.  As soon as it was in use, the download problems ceased.

I am keeping a machine with Avast installed so I can assess new versions with a view to continuing with Avast when I believe that the problem has been cleared - soon I hope.

[hake]

That's much better.  Two systems with Avast

I like Behaviour Shield more and more.

The problems have been resolved by going back to system clones, thoroughly cleaning out Avast 5.0.677 then clean installing Avast 5.1.889 (no 5.1.864).  It seemed impossible to get Avast working once 5.1.864 had been on the system and I did not have a recent clone to fall back on for that system.

One system refuses to behave with Avast so AVG it must be on that one.  :'(

I wish I could be more informative.  It's taken a whole day of intense activity to get to this.

[schmidthouse]

That's much better.  Two systems with Avast

I like Behaviour Shield more and more.

The problems have been resolved by going back to system clones, thoroughly cleaning out Avast 5.0.677 then clean installing Avast 5.1.889 (no 5.1.864).  It seemed impossible to get Avast working once 5.1.864 had been on the system and I did not have a recent clone to fall back on for that system.

One system refuses to behave with Avast so AVG it must be on that one.  :'(

I wish I could be more informative.  It's taken a whole day of intense activity to get to this.

I can understand how frustrating and time consuming this process can be.

If you should choose to try again later, I would suggest you follow these instructions to completely remove 5.1.864 and all its remnants.
Remenber, now that you installed AVG, you will have to be extremely diligent in removing that software and all of it remnants for any remnants left from any other security software  you have had installed in the past can invariably corrupt the installation of Avast.
Here are the removal tools for AVG: http://www.avg.com/us-en/download-tools

If you have had v.4.8 installed or v.5.0 or 5.1(beta) and had issues with the functioning of the version or an install of a newer version over top did not work properly, there is a possibility of File corruption. I have found this process to be extremely effective in many situations. Consider executing a ‘Clean Install’ using this format.
 I recommend you follow these instruction in the order they are presented

 Please download the latest official version of Avast (5.1.889) for the product you need and save it to your HDD:   

        Free AV: http://files.avast.com/iavs5x/setup_av_free.exe       
        Pro AV: http://files.avast.com/iavs5x/setup_av_pro.exe       
        Internet Security: http://files.avast.com/iavs5x/setup_ais.exe

Then please download aswClear5.exe (Clean up Utility) http://www.avast.com/uninstall-utility and save it to your hard drive where you can access it easily.

1. IN NORMAL MODE, Please go to Start/Control Panel/Add and Remove Programs and choose Avast and click Change/Remove, and then Uninstall from the options listed. Once the uninstall process is completed, Reboot your computer
2. When up and running, Reboot again, this time into 'SAFE MODE' and find the (aswClear5.exe) download you saved to your hard drive and run the Clean up tool. Make sure you first choose the version from the list supplied in the tool that you want to cleanup and then run the tool by choosing Uninstall; your computer will automatically reboot.
3. Once up and running in Normal Mode, if you choose too, follow the NOTE BELOW, before finally installing the latest version of Avast you saved to your hard drive.
Remember, if you have had more then one version of Avast installed on your computer, you need to choose the version in the Clean up tool that you have had installed on your system one at a time. If you have had both v.4 and v.5.0 installed, then you need to follow the ‘safe mode’ process twice; once for each version separately.

NOTE: It has also been suggested to run CCLeaner after you Reboot and before the Clean install of Avast.
CCLeaner is Free and Safe System Optimizing, Privacy and Hard Drive Cleaner> http://www.piriform.com/

If you have any problems please feel free to let us know.

[hake]

Thank you schmidthouse.  Those were very helpful comments and I appreciate the time and trouble you have given to help me.  I have a notion that something to do with the network connection or proxy (port 12080) must have gone wrong deep in the system.  I was only able to fix the problem by restoring from clone backups predating the update installation of Avast free 5.1.864.  My desktop systems have 2 drives so this is simple.  It is less simple for the laptops which only have one drive each.  I have clones but the restoration is more messy and I am going to do this in a few days time.

I wonder if Avast could consider a repair kit for those who have been unfortunate enough to have installed Avast 5.1.864.  I think that the possibility of damage by 5.1.864 to lower level network stuff should be looked at.

I uninstalled Avast 5.0.677, also ran aswclear5.exe then clean installed Avast free 5.1.889.  It works great.  As I remarked earlier, I love the Behaviour Shield and with the probable demise of Threatfire, it is just what I need.  It doesn't disturb system stability like Threatfire sometimes did.

Avast is sooooo elegant and fast compared with AVG.  

[hake]

Alas, the problem remains.  I did all that I was advised to do by schmidthouse (a totally clean install) but to no avail.

I find that downloads which are not done through Web Shield (e.g. Malwarebytes updates, Spybot- Search and Destroy updates, SuperAntispyware updates, Avast updates and Outpost Firewall updates) seem not to be affected by the problem, only stuff coming through the Avast proxy port 12080.

I can do no more and await a later version.

While running Avast 5.0.677, the problem did not occur.  Unfortunately, I cannot reinstate 5.0.677 because of database update incompatibilities ('invalid file' message).  Yes, I installed it.  No, it wouldn't accept the database updates.

I did try some web downloads with the out-of-date v5.0.677 and found that they worked, i.e. no file corruption.  It would seem therefore that Avast 5.1.889 has not broken my systems.

I hazard a guess that this problem only affects Windows XP systems since Windows 7 users seem not to experience it.

Shame that Avast has this flaw.  It performs beautifully but that is irrelevant when it cannot cleanly pass web downloads.