When I try to download 5.1.864 version from Avast's site the Cnet download site offers me the old 5.0.677 version. Why I can't download the new version? Is the stable 5.1.864 even out yet?
To answer the OP's question: The reason is that v.874 is a beta version for those having problems with the pre-release version (v.864), and this version is available on the forum page, as you discovered.
The proper way to uninstall and do a clean install of Avast is as follows:
Save a copy of newest version of Avast (Beta build 5.1.874)
for the product you need and save it to your HDD:
Free:
http://files.avast.com/files/beta/5.0.874/setup_av_free.exePro:
http://files.avast.com/files/beta/5.0.874/setup_av_pro.exeAIS:
http://files.avast.com/files/beta/5.0.874/setup_ais.exe2. Download the Avast Uninstall Utility
http://www.avast.com/uninstall-utility and save it to your HDD (it has uninstall tools for
all Avast versions and products).
3. Disconnect from the Internet at this time.
4. Go to Control Panel and uninstall Avast through Add/Remove Programs if possible and reboot.
5. If Step 4 fails, boot into
Safe Mode (hit F8 repeatedly) and run the Avast Uninstall Tool.
6.
Reboot.
7. Install the newest version of Avast and
reboot.
8. Get Internet access and register your copy or add the license key for Free, Pro, or AIS.
9. Update the Avast definitions.
Please let us know if this fixes your problems. Thank you.