Hello again

I don't get this: Quite often when i modify some templates, i will get a space between the lines. So it's like
1. Line
(A half, empty line)
2. Line
So there's a line spacing of 1?

Then the weird thing is, that if i change the code back to the original (which didn't have a line spacing of 1? before) I get the space

I don't get it!
What have i done wrong?