Varying Image size when using Scale

Hi Everyone,

This is the first time I have had to post looking for help but this one has really stumped me. I could be doing something really stupid.

I have a content type called news with an image field. I am using ImageCache 6.x-2.0-beta12 to scale this image to 320px × 240px.
I then use views to display a list of all news stories showing the image.
The problem I have is some of the images display as 320px × 240px and some 120px × 90px; it seems to be completely random which ones work correctly. I have tried different images, file sizes and resolutions but it doesn’t make any difference still seems random. I have attached a screenshot to show exactly what I mean.
I also tried using resize but then I get all the images the same size but some are obviously still 120px × 90px and then resized in the html.

Any ideas would be greatly appreciated.

Thanks in advance
Yogi