Syntax Highlighter Plugins Displaying Wrong

I’m having some problems making syntax highlighers work in my blog. I’m using the Mandingo 1.3 theme, and i’ve tried SyntaxHighlighter and Google Syntax Hilighter.

Both of them convert the code into a nice little box (i belive using java script) and everything looks as it should except that every other line has different heights i.e. 1,3,5,7 are tall, 2,4,6,8 are short.

You can see what i mean on my page here.

Can anyone help me?