Lots of laptops use an accelerometer to detect that the computer is falling. When that happens, the computer parks the hard drive heads to prevent them from bouncing on the HD platter. Apple calls this the Sudden Motion Sensor. On Thinkpads it's the Active Protection System. Other laptops have similar features.

The problem is that loud sound can trigger the accelerometer and park your hard drive heads. For audio work, especially during takes, this is very bad: when the drive is parked, you can't write to it, and when you can't write to disk, you can't keep recording. On Pro Tools you'll get an -9073 error; on Cubase and Nuendo you'll get a dialog that says "Recording Error: Too many tracks recording."

I figured this out after years of frustration -- I often track with a laptop in the same room as hundreds of watts of angry tube amps, and during those sessions I had repeated, mysterious problems with Cubase dropping out of record. Learn from my pain: At a bare minimum, disable the motion sensor for any tracking work.

On a Mac, disabling the Sudden Motion Sensor is easy:

1. Start Terminal (in /Applications/Utilities)
2. Type sudo pmset -a sms 0 and hit enter
3. Enter your administrator password

Then to re-enable: sudo pmset -a sms 1

I'm still doing some testing to confirm that this solves my problem, so please report back if you try it!

Here’s the last time I got bit. My laptop was three feet in front of the Marshall cab.

 (There's a longer version of this post on my personal blog.)

Hi Scott, Thanks! this will go to my students and interns along with some other key performance settings. This was causing me some real problems recording live international Hip-Hop events on my MBP. You don't often hear rappers at the top off their sets saying "yo, turn the bass down". We should make a Tape Op apple script to turn off the sensor and turn off the spotlight search engine and set the energy saver hard drive to never go to sleep. We'll call it:No Sleep, No Search and No Bumps in the night....Well the name could use work. :)
All my best
Dan

Hi Scott, I'm making some experiments and seems that disabling sms does not resolve the issue. I'm posting the detailed thing
on gearslutz..
Ganzo

Sorry forgot to write down the link http://www.gearslutz.com/board/music-computers/646950-macbook-sudden-motion-sensor.html#post7285625

A solid state disk, while pricy, would likely fix this problem. I use a MacBook Air without the issues you describe.

One of my old bands wanted to get some basic "boombox" recordings of our songs, just so we could have something to take home. Our drummer balked at my suggestion of just doing a few raw takes on my 4track. He kept insisting on using his Mac laptop. We had a drumkit and two 4x12 cabs blasting in a space the size of a bathroom. We couldn't even get through a single take and most of our songs were under a minute long!

This whole ordeal went on for an hour.