As I understand it the <pre> tag is supposed to preserve spaces and line breaks in the html. Safari instead replaces many letters with blank spaces. The file at http://davidmo.com/bugs/bug.html should display the letters a through z but it only shows some of the letters.
Created attachment 41414 [details] Has the letters a-z inside a <pre> tag. They do not show up correctly. Simple demonstration of bug. Has the letters a-z inside a <pre> tag. They do not show up correctly.
I cannot reproduce this (and we'd certainly hear a lot about this if this were a widespread issue). Chances are that font rendering is somehow confused on your machine - either a broken font is installed, or system-level font caches are corrupted. Actually, all comments in Bugzilla are in <pre> tags.