Picture frames

Hi everyone -I was wondering if anyone out there has an answer for a little problem I’m having. I added a 1px border to a load of images on a site I am building. The border looks fine in the work area and there seems to be no problem at all. But as soon as I do a test, or publish the movie the border gets disrupted. Is this a matter of picture format, maybe? Any ideas otherwise? Please see the attached pictures for an example of what I mean.