I found the problem. Either you edited an id in your themes default.css or the theme edited it. The edited style is:
right: -330px !important;
Since it has
!important, when you hover, the style cannot change to
right:0px; because the important is keeping it set at 330px. So you would need to delete this in your theme's default.css
If you want the style to be 330px instead of 328px by default then you would need to edit wp-content/plugins/wp-flybox/includes/css.php and change line 140 which has the array that contains the default widths.
1 => '292', //facebook
would need to change to
1 => '294', //facebook
Increasing the default width by 2px is basically doing the same thing you or your theme is doing without having it stuck with
Please try this and let me know whether or not it worked for you.