images showing up at different sizes

Hi Tony!
I love your plugin – thank you for all your hard work! So I’m using it to pull in random products to a page and it works great, the only problem I’m having is that it pulls my images in at different sizes each time. All my images are exactly the same size, so not sure what is happening to cause this.

Any ideas? Thanks so much!

http://wordpress.org/extend/plugins/ecwid-useful-tools/