* Hardware acceleration is OFF * Sierra 10.12.5 / Firefox 55.0.3 I have a tricky and very very frustrating issue. As a long long shot, I am hoping at least 1 other person has seen it, so demonstrate to me, I am not alone. Behaviour observed since new install of Sierra 10.12.5 on a new SD harddrive (from yosemite on a sata), Fresh install of Firefox 55.0.3... Intermittently, the trackpad will go crazy. Just moving over something clicks it. But it does this not only in firefox but all apps. opens things on my desktop (when this "thing" is really bad) and opens files in my Finder. Essentially you have lost control of your MBP. -- So I started troubleshooting about 1 month ago. The issue is known on the web, but no one is saying it only happens after Firefox 55 is opened and used after some time. Then stops and mouse/trackpad returns to normal once Firefox 55 is shutdown. This is where my troubleshooting has got me to. -- Problem is intermittment. For example, I can use Firefox for an hour and then it will start. Other times I can only use it for 10mins and it will start. Some days it is behaving I can use firefox for 3hrs before it starts... -- By Mouse/Trackpad craziness -- I mean the cursor is moving by itself. It has different degrees of severity, Sometimes, its just slow.. like its processing somethign and not repsonding.. Next level of severity, is by just moving the cursor with your trackpad, whatever you move-over to go where you want to go, gets clicks. Next level of severity, is when it the cursor jumps around all over the place.. and opening anything it lands on -- it darts like a mad man. ---- Troubleshooting suggested solutions from others on the web say * it is an old battery. I have replaced mine and it worked well for a few weeks and now only happens when I open Firefox. * say reset PRAM, I do that and nothing changes * say shift control, L and power button. I do that and nothing changes * say boot MBP up, holding option button, and it may work for a while and then goes crazy again. * say in accessiblity setting, uncheck/check the ignore trackpad if using wireless. I do this and nothing changes. * say the Bluetooth setting is ON and causing it. My bluetooth is setting is OFF. I only use the pre-installed trackpad FYI - I tested it with a connected mouse, and the same thing happens. Only if you shutdown Firefox does the mouse return to ---- So I had been thinking it is purely Sierra MacOS related and nothing to do with Firefox. Then I purchased a new battery, recalibrated the battery and it work perfectly for several weeks. Then yesterday the problem started again. None of the above listed troubleshooting worked. But what does work, is if I shut down Firefox. Then the trackpad works as normal. This has happened 6 times since yesterday. -- The problem started about the same time I noticed Firefox would not close down/shutdown properly. Not sure what happened but my kittykat was on my MBP late in prior evening and it started beeping.. so she jumped off, and then from then on, Firefox would not shut down and then next day I am observing mouse/trackpad crazyiness was back and Firefox would not shut down properly. -- So I deleted firefox of my MBP. Installed fresh Firefox app from web. I created a brand new FX profile yesterday, and the issue has happened in the new FX profile. It happened before I loaded any addons. So that is sorta like safe mode. When I closed down Firefox (in the new profile with no addons) the trackpad stopped being crazy, and went back to normal. In this new Firefox Profile, Firefox is closing down /shutdown as it is suppose to. But mouse/trackpad craziness continues. -- I have other apps open that shutting them down, does not stop trackpad crazyness. -- The only thing I note about Firefox it is the app that uses the most energy/RAM etc.. but that makes sense as I am using it most. I cannot check if it happens in safe mode, as the issue is intermittent. ---- So if anyone has any ideas. Please post.