This is more of a bug report then anything else. It would seem that setting an image to have a frame and size causes the size field to be ignored. This may be a more recent bug, as it is documented to work here
As proof of the matter I give you a link on your sandbox and a link to my wiki page that is currently having the problem here. Not being able to resize the image is actually causing the css frame to break.
Thanks for your help,
You are not the only one with the same problem You may find something or maybe not at:
http://www.mediawiki.org/wiki/Manual_talk:Image_Administration
In the meantime, you can just make a one cell table and put the image in that cell. Then you can give the table whatever border you want. However, you have to size the image to be smaller than the cell that it's supposed to be in, as it won't resize itself automatically. For instance:
{| style="width:50px; border:5px solid blue;"
|[[Image:Example.jpg|45px]]
|}
makes:
 |
Note that I gave both the table and the image a size.