In the "My Controls" page, when changing "my personal photo", I clicked browse, selected a file I wanted from the file upload box, then clicked inside the box which displays the chosen file to make sure I selected the right file, and when I did that the file upload box re-opened.
I am running Mac OSX 10.5.5 and it happened in both Firefox 3.0.4 and Safari 3.1.2
Here's a screenshot I took.