Bad quality on certain images

[Krillz]

Hello, i'm trying to convert a word file with PDFCreator

However, I've made a lot of images with CorelDRAW (png format), but some of them (not all!) are not printed correctly in the PDF file.

I just don't understand why...

Here is one of the images that cause me trouble

Thanks

[Andreasm82]

Developers can't do anything with a sample file. Could you please post your original and your pdf file?

What's wrong with that image?