When creating a table you may notice that in some browsers cells that have images will grow to hold the image, while other browsers will shrink the cell and squash the image in the process.
The way to work around this is to make sure than any cell containing an image has been given a fixed width, so that all browsers know not to shrink it.
You can do this by placing your cursor in the offending cell and clicking the small arrow next to the Table button:
This will present you with this menu:
In this menu, choose Table cell properties. In the window that appears, make sure that there is a value in the Width field. This value should be at least the width of the image you are displaying inside it.
For more information on creating tables, see this support article.