Squares around images when printing

Hi there

I'm a self taught user who is struggling with an issue on Corel X7 where my printer prints a darker square around the image I have just converted to bitmap.  I am using a solid blue background.  It also does this when I try and add a drop shadow effect.  I have tried breaking the drop shadow apart and converting the shadow and the image to bitmap but it doesn't help.   On the screen it appears as I want it to print, but every time I print,  the darker square appears. I hope this makes sense!  What am I doing wrong!?  Some help/advice would be very much appreciated!  Thanks