Thanks for your concern, Jonathan.
The crash occurred suddenly and I haven't gotten any error window to let me know what had happened.
It usually happened when I tried to write something in the text field of some widget with high likelihood.
And it seemed having no business with specific files, the crashes just happened when typing regardless of which file I was working with.
I also found that some people seemed to had met the same problem as I had, using the Axure Pro under Windows 8.1 OS. But no one knew the reason and how to fix that.
Oh, by the way, I was typing Chinese characters but not English words, may it concern with the Chinese typewriting apps? However, I haven't met the problem under Windows 7.
Thanks for your reply again.