We have had the problem, people on our Forum have had the problem: blue frames in Final Cut Pro X when using custom video effects. Apple have acknowledged the problem and posted a fix.
What is it with computers and blue screens? If you haven't come across this problem, it was caused by some custom effects not rendering correctly.
From the Apple Knowledge Base article:
"In some cases, custom versions of video effects (referred to as "Templates" in Motion) created or modified in Motion 5 for use in Final Cut Pro X may render in Final Cut Pro X as blue frames. Affected custom video effects in Final Cut Pro X can be effects, transitions, titles, or generators.
To resolve this issue, make sure that you update Final Cut Pro X to it's most current version.
Note: If you are actively working on a project, avoid updating Final Cut Pro X until you are finished with the project. Either complete the project in the version of Final Cut Pro X you are currently working in, or ensure that you have a current backup of your events, projects, and Final Cut Pro X. This is so you can revert to the previous state that your data and the application were in if updating or upgrading to the latest version of Final Cut Pro X does not address your issue."
There you go, an easy fix and sorry if you were expecting a complex Terminal hack to get around the problem!