A few days ago, I don't know what happened, possibly nothing but my 13" MacBook Pro trackpad started acting weird. Did I spill water? Food? Shook it? Pressured it? Any of these might have happened, but nothing out of the ordinary that caught my attention.
So, the trackpad started moving around randomly by itself; sometimes clicking around. It was dangerous so I disabled the trackpad from here: 
I've tried:
- Mac restart
- SMC reset
- PRAM reset
- Fontnuke
- Clearing some settings and caches
- Messing with the preferences
Nothing worked to fix it. Even my mouse (Logitech G500) was messed up, the left button is not clicking and movement kind of clunky.
Interestingly when I login with my guest user account, my mouse works fine until I start using the trackpad. After using trackpad my mouse gets messed up again.
Also after I disable the trackpad while mouse is was connected and after that operation I restart my Mac and do a NVRAM reset, my mouse works perfectly fine. As long as I don't disconnect my mouse accidently and do something on the trackpad.
After 2 days my trackpad still has issues but it is not as crazy as it used to be. Now, it doesn't run around randomly clicking around, but I cannot control it properly either. Trying to make a shape with the trackpad is very difficult because it starts jumping around. It's also still messing with my mouse, but this time instead of the left button it started messing up the right button of the mouse. Why?
It seems like this is a software problem and how can I fix it?
Best Answer
It's probably moisture.
I experiencing something similar after being caught in the rain with my MacBook Pro. Working outside because the weather was nice, I got caught in a slight drizzle of rain. I immediately shut the lid and ran inside.
It didn't get wet enough to cause damage, but somehow wet enough to mess with the clicking function of the trackpad; it would sometimes "lock" in the clicked position, not register clicks, or click erratically.
What I did was put my MacBook Pro in a Zip-Loc bag with several desiccant (silica gel) packets and leave it overnight.
In the mid-morning, I took it out of the Zip-Loc and the trackpad was working again.
I save these packets in a jar; they come in the packaging of products I buy. I will throw some in my camera bag where I keep my lenses and I will put a few in my briefcase where I keep my laptop.
If you save them, they're free, but they are also extremely inexpensive on Amazon or eBay if you don't have any available and are in dire need.