If you recently did a re-install...you could be running on a trial version and need to activate again, maybe. The trial versions cut lines through the images.http://craftedge.com/activation/activate.html
OR, even though you put in a new blade...there could be teeny tinny paper pieces below the new blade...take it out and use a vacuum on the blade housing, or I have even just put a fine wire or tooth pick in to get the debris out. This could be making your blade not seat completely in the housing.
Or, you have the housing screw in tight, but it is crooked. Make sure it is properly in the groove.
Try another font to see if it happens with all fonts...perhaps it is the one font.
I can't think of anything else it could be.