Word replaces document images with images from other documents when executing a print function

I create a document with images/photos placed throughout the document (the pictures have been copy/pasted from a non-Word source, ie., websites, etc.); some are located "in line" with text; some are located "tight"; and some may be "in front" or "behind" text. 
Everything looks just as I want. So then I execute a print either to a PDF or to my default laser printer (the problem occurs either way; the problem occurs simply when an executing a print).
The images in the origin document (and therefore the printed result) change to an image I used in another document, sometimes from a previous day. The images swapped in are placed in the exact same position with the same formatting and size as the original image. If the original image was 2"x3" and the swapped in image was 4x2, Word distorts the 4x2 image into the 2x3 space.  Word just randomly (I have not determined how it decides) swaps out my chosen image with another (the image swapped in is always from another Word document always from the same PC (I use MS Word on other PCs on the same local/home network).
This is MS Word 2010.