Yes, I have exactly the same issue with Parallels 9 and Windows 8.1 with same MacBook Pro.
Parallels 9 crashes several times every day, typically when using Outlook and less often with Excel.
Parallels seems more stable if I turn off coherence, but this is not a good solution for me because I need to use multiple monitors to work effectively.
My colleague at the next desk also suffers from similar crashes. He is on Windows 8 not 8.1, so looks like a Parallels bug.
Crashes started a few weeks ago. Unfortunately I upgraded to 8.1 and several Parallels 9 updates around the same time, so cannot definitely point the finger.
Anyway, crashes are annoying and disruptive so I hope a solution arrives soon.....