Hi Zenobia,
I tried running in safe mode but it didn't make much difference as I still got the occasional hang ups.
I think that I have figured out what is happening. With the previous version I just clicked on fix selected and everything had the green ticks in a few seconds but with this version it sometimes takes minutes (recently 29 detections took 11 minutes) to fix and get the green ticks. Going by past experiences with S&D I must have been hitting fix selected whilst the system was still fixing and this led to the screen hanging and Windows coming in with the program is not responding. Whilst fix selected is working 2.4 does not allow you to minimise the screen so it can get a bit boring watching the same screen but I have learned to wait. This problem is still intermittent in that sometimes fix selected does go with its zing of old and fix the detections fairly rapidly.
I hope that this "fix" helps others to understand what is happening and to learn patience with the system. I will continue to post here if this is a false dawn.
Thanks
John