When placing notes or dimensions on a drawing in SolidWorks 2010, you will notice that SolidWorks will try to align the note or dimension being placed with already placed dimensions – via the yellow inference lines:

To prevent this, you have 2 options. The first is to change your System Options and they will never appear again for another drawing. (System Options > Drawings > ‘Disable note/dimension inference’)

The second (which I think is preferred) is to hold the ALT key down when placing the note/dimension. It will prevent those pesky inference lines from appearing for that particular note/dimension and you will be able to place the note/dimension anywhere you like with respect to other notes/dimensions.