Hey patti,
Remember, add ons are not the actual programs. Disable live photo gallery in firefox and you will still be able to use it on your computer. It likely takes away the ability to upload the picture using the program, and believe me, it is something you DO NOT DO. Therefore you have no need of it in reality. But it isn't a problem program, so it doesn't matter in truth if you keep it enabled or disabled, but it can only benefit you if it is disabled, as it keeps firefox more 'clean'
The point is to see if you notice any difference after disabling all add ons that we told you to, including live photo gallery. This is what we are trying to do, it is only temporary, and as you said, you can always enable it again if you find you suddenly need it.
If after a little bit you see that yahoo is still giving you errors, then it should be fine to enable some more add ons as it has been proven that the add ons are not a problem. I will list some add ons that I recommend you
do not enable, so keep reading! Let us know if you get computer freezes after you enable the add ons, or if anything else goes wrong!
You mentioned that your computer is running smoothly now, so the only thing we are trying to fix now would be Yahoo mail. If it still isn't working with add ons disabled, re-enable Garmin, ad block, and quicktime, and check that java, live photo gallery, adobe, and silverlight are enabled.
I recommend leaving your cannon printer and Microsoft word add ons
Disabled in firefox, because you can still use both even without them loaded in firefox. The truth is they usually mess with or slow down firefox, and you will still be able to use both programs, even the printer!! (the printer can still print anything in firefox, even with the add on disabled, you don't need it).
Additionally, You will need to update all your add ons for stability! Use this website to do that:
http://www.mozilla.org/en-US/plugincheck/
Let us know everything that says out of date, or to make it easier, snip it and post the picture here for us to see.