First allow me to apologise and thank you for the response to this question originally posted some time ago. Almost immediately after posting I got overtaken by my day job which meant I ended up doing a huge amount of travelling and have only returned to recording in the past month.
So with renewed enthusiasm I updated my computer, purchased Sonar Platinum and started recording with renewed vigour. Sad to say problem still persists. Quantise freezes, sonar eventually crashes leaving sonar.exe process running, only answer is to reboot.
All drivers are up to date.
I've seen many videos on youtube etc where quantize is used successfully with no crashes so maybe I'm doing something wrong. My process is:
1 select track
2 select quantize from process
3 change values in quantize window
I have found a work around - do not audition within the quantise window - no crash!