Yesterday whilst running my 955 crashed twice, I've never had a crash before in a couple of years use.
Details: I was doing a 12k run, following a suggested recovery workout, navigating a GPX route (transferred to watch earlier via DynamicWatch/routeCourse) and listening to music (MP3 files previously transferred to watch). Once at the start of my run (within first 400m) and again towards the end (~2km to go) the watch suddenly displayed the blue triangle. The watch seemed to recover ok with it offering to resume session within a few seconds and just a small amount of data dropped. After syncing Connect reported a couple of new records but these were incorrectly attributed due to the dropped data.