Images not scaling properly across browsers

Images posted in blogs/forum are not scaling properly in FF or IE, I kinda expect it from IE but not FF. Here is an example blog and here is the same page viewed from the forum, the images all look good in Chrome but in FF/IE they are not scaled and instead show the full size, I changed the code to use the original images so users could download the full size images but even when using scale_large, scale_medium, scale_small and scale_avatar the images do not come close to looking consistent across the browsers, they usually look good in Chrome but they are either too large or too small in FF/IE.

I'm thinking the non-scaled images might be hurting readership since the images are showing up so massive.

I barely notice it. I was wondering why users said it looks fine. I was always a Fire Fox user.