Q: Since latest update (today), trackpad, both internal and Magic Trackpad, have been going crazy. Can't use either one.

Open Disk Utility (Applications - Utilities - Disk Utility) then repair Disk Permissions at least 2x. Restart, retest, post back with results.

There are several possible causes for this issue. Take each of the following steps until it's resolved.

1. Follow the instructions in this support article.

2. Reset the System Management Controller.

3. If you're using a Bluetooth trackpad, investigate potential sources of interference, including USB 3 devices.

4. A swollen battery in a MacBook Pro or Air can impinge on the trackpad from below and cause erratic behavior. If you have trouble clicking the trackpad, this is likely the reason. The battery must be replaced.

5. There's a report that a (possibly defective) Thunderbolt Ethernet adapter can cause the built in trackpad of a MacBook to  behave erratically. If you're using such an adapter, disconnect it and test.

6. There's also a report of erratic cursor movements caused by an external display that was connected but not turned on.

7. If none of the above applies, or if you have another reason to think your computer is being remotely controlled, remove it from the network by turning off Wi-Fi (or your Wi-Fi access point), disconnecting from a Bluetooth network link, and unplugging the Ethernet cable or USB modem, whichever is applicable. If the cursor movements stop at once, you should suspect an intrusion.

8. Make a "Genius" appointment at an Apple Store to have the machine tested.

rkaufmann87, your suggestion fixed my issue...thank you.

Your welcome.

not happening.. im still stuck with the issue.. i have to keep my palm on the trackpad to make it stop...

pls help..

thank you!!

You might want to consider starting a new discussion. Since this one is marked solved, less people are likely to look at it.

Fixed me too, rkaufmann87 but only after 2nd restart.  Yippity!

Your welcome.