Don't get me wrong. Notepad++ is a great piece of software. But there are some little gotchas that'll appear every now and then when using it.

When you're dealing with HTML, PHP, and JavaScript files, especially when you're creating them from scratch, starting with a new file, look out. Double check and make sure that the encoding is UTF-8 (which is the default encoding) without BOM, because if there is a BOM, it'll wreck havoc. Lots of havoc.