If you encounter problems only with Internet Explorer with image gallery, it's probably your theme's fault. Press F12 from your keyboard. Then press the arrow (CTRL+B) and go back to IE without closing the window. Click on the "broken" image and return to F12 (Developer Tools). In the right table, make sure that the style button is enabled and you will see all the check boxes with or without a line (strikethrough). Try to check and uncheck the boxes to see which element is the wrong one. If you have figured it out, then go to your actual file style.css of your theme and remove this line. Reload the page with IE and it will probably be OK.
I just wanted to share it with you because I was searching for hours about this and I didn't even know about F12. :-)