Wow, I never had it crash without a trace, until just now! I was editing some text within a drawing, and had the program vanish just like you described. Normally I get an error message, but not this time. Very bizzare.
I also have random crashes in VW 11.5. Never happened in any of the other versions I've used, but since upgrading to 11.5 I get a crash or two a week that really sets me back if I have not saved recently.