Q: Safari frozen.  Safari Preferences is not accessible

Are you able to Force Quit Safari?

Russ

Did you Force Quit the Safari browser and then attempt to restart it in safe mode?

• Force an app to close on your Mac - Apple Support

You may be able to stop any existing page information from re-appearing if the

automatic setting in the browser is set to not re-open the content again. This

also works when logging in, to hold the shift-key down, as in Safari safe mode.

• Automatically re-open windows, apps, and documents on your Mac - Apple Support

If the notice you see in Safari is due to a pop-up or adware related fake virus notice

the item may be diagnosed from this page in Support with several ideas presented.

• Stop pop-up ads and adware in Safari - Apple Support

Also if you have a second browser to go online, you could get the Etrecheck app

and run the report to see what it tells you. Read the maker's instructions pages.

http://etrecheck.com/#about

To get a newest version of AdwareMedic (formerly from TheSafeMac) to remove

many kinds of adware, and other issues, see the latest product linked via here.

http://www.adwaremedic.com/index.php

Not sure what the actual cause of this problem is; however a few good ideas on how

to discover the happenings in your OS X can also be found by using posted methods

by Linc Davis in the Apple discussions topic threads where he has replied.

Good luck & happy computing!