FM12 Save as RTF 1.6 Crashes Intermittently

FM 12.0.2.389 in Windows 8 Pro (not 8.1). Only FM and Windows Explorer open. Is there a known issue with Save as RTF 1.6 in FrameMaker 12? I would like to be able to predict the crashes, because it killed me on a deadline yesterday.

Often, when saving an unstructured six page FM as RTF 1.6, FrameMaker crashes (and closes). I get a message that FrameMaker has stopped working, and anything I select results in FrameMaker closing and when I reopen the FM I have to reset the file lock.

And, other times, the RTF is created.

And the crash or successful save has happened without any changes to the FM in question. I cannot identify any factor contributing to the crash, when the crash happens (so I cannot provoke or predict the crash), but when the crashing starts it persists for a while.