Accessibility ignore built-in trackpad option

I'm going to take a winger here, but it seems to have worked for me recently and also with a trackpad problem with my old 17" Powerbook. Try plugging the charger cord into a different receptacle. You may have to try more than one receptacle to find one that mitigates or eliminates the problem. Since moving my charger to a different receptacle, my trackpad issues have stopped. It did seem to take a few days but I haven't had to go into Preferences and change anything for over a week now. Before I was doing that 6+ times a day, sometimes within minutes of previous changes. I can't explain why it works. My old Powerbook developed a cursor with a mind of it's own, opening files, flying across the screen, all on it's own. With the Powerbook, I took it into a different room to charge. Once the symptoms disappeared, I found a different receptacle near my usual workplace (i.e. lounge chair) that was suitable. Strangely enough, my previous 15" MacBook Pro worked fine off of the "bad" receptacle.

FWIW, I don't think it's a bug. I tested two different Magic Mice on a 2015 MacBook and a 2013 MacBook Air, both running Sierra 10.12.1 and I can't reproduce your problem. You could try resetting NVRAM and/or the SMC.

Reset the System Management Controller (SMC) on your Mac - Apple Support

How to reset NVRAM on your Mac - Apple Support

I have the same issue. Another thread said to turn off Ignore Trackpad in accessibility, restart, and then enable ignore track pad again. Tried this and no luck. Have also done SMC, etc. A number of folks are having this issue. Like you I have to do it manually with each new restart. The ignore trackpad is Checked on restart but the trackpad still is working. Like you, if I uncheck it and recheck it, things will work until I restart my Mac Pro. This has started when I updated to Sierra.

I had the same issue, and I think I've solved it. You need to delete the built-in trackpad's preferences file and let the system rebuild it, which you can do like this (back up just in case, but the system auto-rebuilds pref files so it shouldn't be an issue - also note that this will delete any trackpad customizations - speed, etc. - that you have, but the idea is to disable it anyway...):

1. Go to Finder, hit cmd-shift-G to get to the "go to location" popup

2. Type ~/Library/Preferences

3. Find the file "com.apple.AppleMultitouchTrackpad.plist" (without the .plist if you don't have show extensions on) and drag to the trash

4. Restart the computer

Not sure if this will work for everyone, but it solved the issue for me.

Before I try this, do you think it will solve my problem. I do not use any of the trackpad options listed in Preferences under Trackpad. However, the system keeps resetting Tap to Click. It can happen after 5 minutes, 5 hours, or any random time. Usually it happens while I'm working on the computer so it's not related to putting it to sleep. The other issue is that I use Enable Dragging with Drag Lock in Accessibility, Trackpad options. I click the radio button and it may stay clicked for any length of time (a minute, an hour, etc). While I've said that it's not related to sleep, that is not quite true. My choices are always undone when I wake the computer. Do you think that deleting the built in trackpad's preferences files will correct these issues? (MacBook Pro 13", Early 2015, Sierra 10.12.2)

Thank you....fix problem...