When I write PHP code, I often use HTML code to format the output. The problem is, that sometimes the syntax highlighting for PHP stops working, or even changes to HTML syntax highlighting sometimes

I am using CoffeeCup Free HTML editor 2009 on a windows Vista Home Premium computer. I haven´t tried to recreate this on other computers, but the HTML editor keeps doing this over and over again. This error occured on the 2008 Free HTML editor too (I upgraded yesterday).
I have attached some images to help describing this problem.
Working1.png is the code in the editor directly after I´ve opened the document and scrolled down ti the right place. Working2.png shows the same code block after I have pressed enter and then deleted the empty row I created (You can see where he text marker is). The syntax highlighting disappears directly when I insert the empty row using enter.
Have anyone noticed the same problem, or have a solution for this?