I am having the same problem. CWYW works up until I have pages worth of text boxes, images, tables, etc.
I messed around copying and pasting parts of the document that was crashing into a new document to see if I could isolate which component of my document was making Word crash upon trying to update my bibliography and it seemed as though it was the sheer amount of formatting and data that the CWYW plugin had to look through that caused it to crash because the larger the portion of my document I tried to use, the more quickly it crashed. There was an intermediate stage where it would begin to update my bibliography and then crash half-way through.