Surprisingly, though, sometimes the problem has nothing to do with the applications you’re running at all and instead is all about the disk space you have available. It’s not a problem that comes up too often because being built on a Unix foundation, Mac OS X actually has decades of memory management evolution under the hood, but sometimes you can get a program that gets bigger and bigger in memory and causes problems. Ah, yes, the dreaded “Your system has run out of application memory” error in MacOS X.