Try troubleshooting extensions and third party plugins.
From the Safari menu bar click Safari > Preferences then select the Extensions tab. Turn that OFF, quit and relaunch Safari to test. If that helped, turn one extension on then quit and relaunch Safari to test until you find the incompatible extension then click uninstall.
If it's not an extensions issue, try troubleshooting third party plug-ins.
Back to Safari > Preferences. This time select the Security tab. Deselect: Allow all other plug-ins. Quit and relaunch Safari to test.
If that made a difference, instructions for troubleshooting plugins here.
You can avoid losing documents by backing up your files on a timely basis.
Thanks for responding.
There was only one extension that could be the issue since it was enabled before this started happening: AdBlock.
I went ahead and took your suggestion and selected OFF, quit and relaunched Safari. Hopefully, this will be the cause.
The lost docs are when I am working on something like an email or word doc and then momentarily go over to view something on Safari and then it freezes and too late to to go back and save the data.
Another problem unrelated that just started happening:
screensaver sleep mode freezes up and will not wake by clicking a key or moving the mouse and I must do a cold reboot.
I have tried both methods now and have again experienced the mouse/keyboard freezing up. To narrow down the diganosis, the only time it happens is when I am scrolling my Facebook page which now leads me to think it has to do with a compatability issue between Facebook and Safar. I forgot to mention that on my FB page only, sometimes the page goes partially black and I have to refresh it to reload/bring it back up. Why it causes complete freezing up of all keyboard and mouse functions is still a mystery.
As I suspected, this seems to be a big problem with other users and AdBlock seems to be a culprit in this issue so I deleted it even though I had the Extension tab turned OFF:
Any other suggestions besides using another browser (i.e. Firefox) for viewing FB?