McAfee SiteAdvisor has been blocked for your protection.

Why was it blocked?
This add-on causes a high volume of crashes and is incompatible with certain versions of Firefox.
Who is affected?
Users of McAfee SiteAdvisor below version 3.3.1 for Firefox 4. Users of McAfee SiteAdvisor 3.3.1 and below for Firefox 5 and higher.
What does this mean?

The problematic add-on or plugin will be automatically disabled and no longer usable.

When Mozilla becomes aware of add-ons, plugins, or other third-party software that seriously compromises Firefox security, stability, or performance and meets certain criteria, the software may be blocked from general use. For more information, please read this support article.