1- Make a copy of the project.
2- Run in safe mode. this will load one plug in at a time.
3- Try to save after loading each plug in one at a time.
Test: does it save a New (blank) project ? if it does that might be a good idea that it is a plug in.
it could very well be a plug in that is causing the crash upon save.
that's all I got man, wish I could help you more.