why does Firefox displays my thumbs in  vertical order, in explorer there is no problem. i changed the thumb size but it doesnt help. i am displaying 3 thumb in a row at explorer, when i open it in ff it turns to 1 col 3 images :(
sorry for my poor english.

Check out SIG Pro thumbnails display in one column. Problem explained & solution provided .

For me, it worked with adding the following to my CSS:

But there are suggestions to other solutions as well.