Fix a couple of image re-sizing issues on a WordPress site

I'm having a few problems with one of my WordPress sites, http://reswpthemes.com. The slider images are not re-sizing correctly (they should be displaying at 960 x 400), and some of the thumbnails (look in the popular posts widget) are not re-sizing properly either (too big). I've tried regenerating the thumbnails but this didn't help.

The theme is Style by MyThemeShop. I've asked in the support forums but the support staff are running out of ideas and only provide limited help. I'm at the stage now where I need someone to go under the hood and take a closer look.