Update: It crashes too just when using the numeric rating, it just takes longer.
Sorry for the trouble with crashing, try installing the updated DLL found in this article to fix the crashes: Lightroom 5 crashes rating, flagging images | Windows
Let us know how that goes for you.
Thanks, that seems to have fixed it!
I have lightroom 5.5 which crashes. I have tried the ui.dll file but this does not cure the problem. My old 5.4 worked fine. I also find that if I try to use "Lightroom mobile" from the help drop-down list it will always crash. I can normally work for about an hour before it crashes.