I was in the middle of editing a Java class (i.e. just typing) that I had just been method-testing in the debugger with the JUnit plug-in, when Idea 8 just vanished - no error messages, no warning. There is nothing unusual in the log file.
When I restarted it, it reparsed the whole project, but took me back to where I'd been editing with no code lost, which is a relief. However, that's a scary 10 minute distraction I really didn't need.
Running under Windows XP.
If you'd like any more info, please ask.