Oops, my columns are messed up.
A few months ago, I added the following code to the functions.php of my theme:
add_filter( 'loop_shop_per_page', create_function( '$cols', 'return 48;' ), 20 );
This worked fine: 3 products per column (plus a sidebar to the right), 16 rows on a page.
Now it's a mess. One row has 2 products, a second one 3, another row only one...
What should I do? I tried removing the code I added, but that doesn't work.