This only happens in SW2018. I did not have this problem in SW2017.  I have downloaded and installed SW2018 sp1.0 and it still happens. The only way it seems I can fix this, is when SW freezes, to shut it down and start it up again. After that it seems to work ok. But this is highly problematic and annoying as I end up having to do this several times a day!

Does anyone have a fix for this? It appears to be a bug in SW2018.