Math & Science ⇒ New Line in Equation

[Stefan Kottwitz]

The previous example worked for me as well. Perhaps remove the .aux file and compile again. A problem in the .aux file can prevent compilation and could show strange errors.

Does LaTeX only work correctly on a PC? I'm using a Macintosh.

It should work fine also on a Mac. One of LaTeX's benefits is that it runs on many systems and produces the same output everywhere, except for some operating system basic differences such as input character encoding.

Perhaps post your file here differently, as attachment, instead of copy and paste.

Stefan