Which browser/os are you using and how are you moving the cursor to the beginning of the next line? I can't reproduce the behavior you described when using the arrow keys to move the cursor to the beginning of the next line (I'm using Firefox 3.6.3 on Linux). If you want to disable that feature at all you can do that using the userscript.js file as described at
http://forum.dokuwiki.org/post/17159. Please reopen if you were actually using something different than the enter key for moving to the next line.