Bugs & Fixes: 10.5.5's Font Display Problem
September's Mac OS X 10.5.5 update has been the subject of the last two Bugs & Fixes installments--the first on hassles with third-party apps, the second on why you may not have noticed all the promised fixes. Let's go for a three-peat, with another 10.5.5-related issue.
The OS X 10.5.5 update introduced a rare font display problem. The problem occurs only if you have a PDF file that has the TimesNewRomanPS-ItalicMT font embedded in the document and you display it using Apple's built-in software (such as via Preview or Safari) rather than a third-party PDF-viewing application. In the offending apps, the text displays with too-thin lines and generally looks unattractive (as reported in this Apple Discussions thread).
One obvious work-around is to use Adobe Reader to view the document, instead of Preview. Otherwise, you'll likely have to wait for 10.5.6--or some future OS X update--for a fix.