I assume that you mean a kernel panic. Read Resolving Kernel Panics for tips. Also, see OS X: About kernel panics.

Last edited by jchuzi; 11/15/14 06:14 PM. Reason: added Apple page
Jon

macOS 11.7.10, iMac Retina 5K 27-inch, late 2014, 3.5 GHz Intel Core i5, 1 TB fusion drive, 16 GB RAM, Epson SureColor P600, Photoshop CC, Lightroom CC, MS Office 365