"Ask me what I want to do" with regards to updates, will time-out if you ignore or don't see the prompt about an update being available - but that shouldn't happen with the 3.6.x to 4.0.x major version upgrade.

Make sure Firefox is de-selected at the top of the Options> Advanced > Updates tab, where is says "Automatically check for updates to:"

All checkboxes are de-selected, all update and refresh options are disabled.

No sign of any update prompts.

If i click on the command icon of firefox which have not assigned to any URL, about once a week delayed to start, and show the window " checking installed components" and update itself to 4.0. Right after i reinstall the 3.6.14 and it works about a week and it will begin again. The update options remain disabled. So, i know it should not happen, this is the reason why i posted the question. Why happen? How can i prevent? Or let made the version 4.0 errorfree. Let solve the problem with the desktop restoring.

By using v3.6.14, you are not only putting your system at risk, but also your personal finances.

There was a security breach at Comodo which is an SSL certificate provider recently whereby a number of fraudulent certificates were inadvertently issued. These allow a hacker to impersonate any site including online banking and the Firefox version you're running at the moment will not warn you that the site is a fake. See http://blogs.comodo.com/it-security/data-security/the-recent-ra-compromise/

The fraudulent certificates were blacklisted in v3.6.17 and beyond.

Update to 3.6.17 by clicking Help | Check For Updates. A number of bugs were also addressed in that version which may also fix your current problem.