I disconnected from the Internet.
I performed a scan with Spybot, AdAware, IO Bit Security/ASC, I erased all malwares detected, and I completely uninstalled all these applications.
I performed a quick scan with Windows Defender → OK.
I performed a (second) scan with MBAM: 2 malwares the first time, no malware found this second time.
I uninstalled Avast 4 and Avast 5 with aswclear5.exe (I runned it twice).
I rebooted my machine twice.
I cleaned C: (system disk) and G: (some more program files, to free space on C:).
I installed Avast 5 with setup file setup_av_free.exe / 5.0.594.0 (link given by SafeSurf).
I rebooted twice → Avast seems NOK ! (icon in the system tray with a red mark)
I connected to the Internet and stopped Windows Defender.
Everything is as before: Avast is NOK, nothing is possible !!! The registration key I got for the fourth time is not valid !!! Nothing happens when I try to update, impossible to save parameters, ...
It seems that my Internet connection is not detected by Avast. What must I be able to read in firewall parameters concerning Avast ?
(I am not allowed to view the article
http://support.avast.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=459 , even after having created my Avast account)
Now I am completely crazy ...
I help about a dozen of friends to install and maintain their PCs, I always say them "Update an application only if you want actually solve a problem or if you absolutely want to use the new features of the new release" !
WHY HAVE I TRIED TO UPDATE AVAST, WHAT A MISTAKE ?!? :'( :'( :'(
Pierre