Ok, i've managed to recreate the prob in IE.
A quick way around that is to hard-code the boxes' width to something like 24%.
Currently, as you have 4 columns, the system assigns a width of 25% each, which is a snug fit.
If you edit your includes/modules/featured_products.php (or includes/modules/YOUR_TEMPLATE/featured_products.php) you should see the following at around line 53 (I guess dependent on other alterations and Zen-Cart version):
Code:
$list_box_contents[$row][$col] = array('params' =>'class="centerBoxContentsFeatured centeredContent back"' . ' ' . 'style="width:' . $col_width . '%;"',
And replace with:
Code:
$list_box_contents[$row][$col] = array('params' =>'class="centerBoxContentsFeatured centeredContent back"' . ' ' . 'style="width:24%"',
With this change, of course, you loose the automatic width values, meaning that if you decide to increase or decrease the number of columns you'll have to set this value manually.
However, since you say it was fine before the SSL cert was installed, you might want to try reinstalling that...
Let me know how you get on!
:-)
Mario