Note, siteadvisor is not your anti-virus, it's a mostly pointless extension. Your antivirus is still running in the background regardless of the browser you use.

Also note, Windows XP is no longer supported by Microsoft. It should not be used on the internet, period. It is an unsafe Operating system. you have only one more update to Firefox before Firefox stops supporting XP, which means your browser will also be vulnerable. At this point XP is 18 years old, you need to update to a new OS, either windows 7 or higher, or Linux.

It is that the extension itself is no longer provided and unavailable. Secondarily that is what is known as a legacy addon, which is also in most cases no longer supported.

prometheis_78063 said

Running Windows XP/SP3; Firefox 52.6.0 under the tools/extensions tab: "SOME EXTENSIONS COULD NOT BE VERIFIED" "MCAFEE SITEADVISOR 3.7.2 COULD NOT BE VERIFIED FOR USE IN FIREFOX AND HAS BEEN DISABLED" No visible way to enable it???? why is my security software disabled in the first place??

Versions of the McAfee Site Adviser extensions that are before 4.0.0 branch which includes the 3.7.2 you have are being blocked (for almost two years now) due to startup crashes it was causing.

https://blocked.cdn.mozilla.net/i1245.html - McAfee SiteAdvisor lower than 4.0 has been blocked for your protection.

for reading only Bug 1286368 - Block old versions of McAfee SiteAdvisor (pre 4.0.0)

This was a Extension that was installed by your McAfee antivirus into Firefox. Your MacAfee antivirus software itself was not impacted by this disabling of the SiteAdvisor extension.

prometheis_78063 said

Running Windows XP/SP3; Firefox 52.6.0

Btw Firefox 52.8.0 ESR is the current version for 52 ESR as of today and 52.9.0 ESR out on June 26 will be the last major update for the old 52 ESR branch (apart from any minor updates for security and allowed stability fixes) as the current is now 60.0 ESR.

Firefox 53.0 and later on Windows requires Windows 7, 8 (8.1), 10 to run. Only other option is switch to or dual boot with a light 32-bit Linux distro which are pretty much all free to use however can be a learning curve for some people initially.

https://www.mozilla.org/firefox/organizations/all/ (make sure Firefox 52 is selected on top of page and you select 32-bit Windows version)

https://support.mozilla.org/en-US/kb/end-support-windows-xp-and-vista

Thanks for all the replies. I read that Firefox 52.. was the last version for XP but wasn't sure which extension so I didn't allow FF to update (soon to be corrected). (As it turns out, I'm already running Firefox 52.8) I will continue to leave SiteAdvisor disabled and yes I know XP is an 18 year old OS, it's also still the 3rd largest OS in use today! Unfortunately XP is no longer supported by MSoft and now the add on software that used to run on XP has also been updated for WIN 7-10, ah well us old schoolers like to run it till the wheels fall off....thanks guys!

The fact that it is the third largest OS (which is not actually true, it's the fourth largest Windows OS, with 3% of the market runs XP) means that it is still a viable attack target for malware authors and hackers, so you should upgrade to windows 7 or later, or Linux asap