I downloaded the new version of avast home edition 6.0 but when i start the installation it is canceling what can i do please help me as soon as possible… Thank you 
Which is the error message?
Which was your antivirus before avast? How did you uninstall it?
Which is your Windows?
My antivirus was avira I uninstalled it and then I downloaded avast… there is no message it just exits the instasllation… I have windows XP
Run the Avira uninstall tool and try again.
http://thewebatom.net/uninstallers/security-software/
i still can’t install avast… it’s like i run the installation and i follow some steps but i have to click fast… if i am not to fast the window just disappears… I really can’t guess what’s the problem…
Other security related software installed…??
Which Service Pack on XP…??
To me, it looks like by now the waters have become quite muddy and maybe,
starting from scratch would be the best solution.
Make sure that your operating system is totally updated including all the service packs.
Uninstall and remove avast! and Avira and then re-install avast!
Instructions to successfully install avast! 6: You can also download these instructions from: http://goo.gl/4IKlO
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Download the product avast!6 Free:
http://files.avast.com/iavs5x/setup_av_free.exe -
Download the REMOVAL TOOL for your current Anti Virus Program by following the Guide offered here:
How do I remove old third-party antivirus software before installing avast!?
https://support.avast.com/index.php?languageid=1&group=eng&_m=knowledgebase&_a=viewarticle&kbarticleid=574
( The removal tool for avast! Antivirus (should you ever need it) : http://files.avast.com/files/eng/aswclear6.exe) -
Once these 2 programs are saved to your computer in a folder that you can locate or,
to the desktop and, you can easily identify these 2 files, DISCONNECT FROM THE INTERNET -
Go to the Control Panel > Select add/remove > (Programs and Features in Windows 7)
select your current antivirus program and select uninstall. (Allow it to uninstall all features of the program) -
Reboot your system.
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Run the removal tool for your old Anti Virus Program saved in step #2
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When the tool finishes running, again Reboot your system.
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Install avast!6 Free by running the program downloaded in step #1
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Shut down your system – Reconnect to the internet – Start your computer.
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Avast!6 Free will now be installed and will update it’s virus database.
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Register your new avast!6 Free product by selecting the Register Now button.
If you need more help, get it from here: http://www.avast.com/registration-free-antivirus.php
This will give you a clean install since you’ve removed all remnants of your old AV and also totally remove all remnants
of the original failed install of avast!
Let us know if this takes care of your problem or if you still need further help. 
I have service pack 2… Bob thank you for your advice i will try that…
Update to SP3…!!
It doesn’t work Bob thanks for you’re help and everybody’s help…
Did you update your XP to SP3 yet…??
What doesn’t work ??? You’re welcome but, is your problem now solved ???
Do i need to uninstall my service pack 2 before i install service pack 3???
NO
I installed service pack 3 but no changes
Now that you have SP3 installed, reboot and read again the complete topic. Follow the instructions again to remove ALL remnants of ALL older security tools you ever HAD.
Then run the removal utility for Avast.
Better yet, run the removal utilities (for Avast and for older security tolls) under Windows Safe Mode so to reduce potential conflicts.
Then install Avast ANEW, with a new download of the latest stable Avast version.
Once installed, reboot immediately and only then configure it, update the latest definitions and so on.
Please report back.
Do a repair of avast!.
Add/Remove select avast! then scroll down and select repair.
When the repair is finished, REBOOT
When the system comes back up, check and see if the problem is now solved.
My teacher told me that i have a virus that doesn’t let me install my antivirus
E:\Images\CapturedScreenPrint\forum-new-topic_VandW.png - Please create your own new topic, here http://forum.avast.com/index.php?board=4.0 in the viruses and worms forum (click the New topic button at the top of the page see image) and we will try and help you there.
We will need more information:
Operating System, what other symptoms you are having.
Read the instructions, download and burn (maybe from another computer), finally use one of this rescue CD’s:
You can check also this comparison article.
Integrate Multiple Antivirus Rescue Disk into One Single Disc or USB Flash Drive with SARDU. The most compreensive cleaning CD.