As explained so many times, you should NOT "disable" the antivirus but, instead, you MUST:
- Add the whole Addon Manager folder to the antivirus Exclusions
No, even if you think the antivirus is "disabled", its low-level service is still running and it might still interfere. That's why we never said to disable the antivirus ( it's a dangerous thing to do, and you cannot be sure you have a real virus instead ), but to configure it correctly.
Also, be sure you don't have a firewall blocking the updater and preventing to update all files.
If you are sure you did both things exactly as explained, then please follow the same troubleshooting suggested here:
http://www.fsdreamteam.com/forum/index.php/topic,24332.msg161589.html#msg161589Post a ZIP file with your Couatl.LOG file, so I can have a look at it.