This is an experience of using the Free Avast Antivirus. During the first few days using the programs everything was working normally, but after some updates it encounters the problem (Visthaux.exe) and my PC starting to get slow big time. The slowness occurrs during Windows Startup and when using Google Chrome browser. Apart from that it prevents the Avast from running at start up and display a message on the system tray "Turn On Avast!! Antivirus (Important) -- by clicking on it, leads to the message options
1. Yes, I trust the publisher and want to run this program
2. No, I would like to verify the identity of the publisher before running this program.
After a few attempts neither one of these options will stop the message to appear on the system tray including restarting Windows will still be the same.
The Visthaux.exe corruption prevented the Avast to turn on during windows at startup. Based on Avast forum (http://forum.avast.com/index.php?topic=39395.0) this can be resolved by updating the Certificate by going to the file itself at C:\program files\avast software\avast\Visthaux.exe and right click on the Visthaux.exe and click properties and switch to "Digital Signatures" page, select the signature in the list and click on "Details". Although the instruction provided by Avast indeed solved the problem and enabled back the Avast Antivirus to run at Windows startup but my PC and Google Chrome browser still slowing as usual.
Running out of ideas what caused the Windows and Chrome browser to lags, I have decided to uninstalled avast free antivirus using its uninstaller which can be downloaded here http://www.avast.com/uninstall-utility.
The un-installation processed must go through Windows Safe Mode to disable all Avast functionality from executing before running the uninstaller.
Once uninstalled, have restarted my PC and everything goes back to normal. Windows Start up and Chrome all running at normal speed as it used to be. That's how i know the Avast Free Antivirus really brings the trouble especially when it encounters the Visthaux.exe.
In addition, after the removal all Avast software registry were removed completely except Visthaux.exe still exist exactly in this registry folder (HKEY_USERS\S-1-5-21-3128674079-2282775409-758013598-1000\Software\Microsoft\Windows NT\CurrentVersion\AppCompatFlags\Layers). To remove this Go to Windows Start>> Type Regedit and run>> Click on the Edit tab and Find "Visthaux.exe" and delete it from the registry. This should put Avast out completely from the system.
Reminder: Visthaux.exe looks a legitimate software provided by Avast Antivirus Software Application. But there is something really wrong with this piece of file, i would consider it as malicious as it slows down PCs and Browsers.