If the screen never stops shaking, it is a problem with sound. To get past this, you need to disable your sound card, play through the scene and then save, exit and re-enable your sound card.
This most commonly happens in the Ceremony of Eternity where Vividos kills Lothian, but I also had it happen in the meeting with Lithos.
The game menu
Pressing the Esc button during gameplay will bring up the game menu. This has 8 options:
Intro - This will show the same introduction you see when you start Ultima 8.
Read Diary - This allows you to load a game from one of the twelve slots you used in Write Diary.
Write Diary - This allows you to save your game in one of twelve slots. You can then load these saved games through the Read Diary option or by starting Ultima 8 and skipping the introduction (by pressing Esc). When starting Ultima 8, it will automatically load the last game you saved.
Options - This allows you to manipulate the options which include Music, Sound FX, Avatar Steps, Animations, Text Speed, Frame Skipping and Speed Limiting.
Credits - This displays the credits.
Quit - This allows you to quit the game.
Quotes - This displays the quotes. This will only appear once you have seen all the Credits till the end.
End Game - Like the Intro, this will show you the animation of the endgame. This will only be available once you finish the game.
In the beginning, only the first six options will appear. Once you finish from any of the options, you will be taken back to the main menu.