could you please take a look at this http://portfolio.amansingh.co.uk/PROBLEMS.htm and tell me whether you can help me with my problem.
The problem might be that the size of the movie clip that the full-sized pictures get loaded into is bigger than the full-sized pictures themselves, so when they get loaded up, they get stretched to fit the size of the movie clip. Kind of like how you can 'stretch' the background pic in Windows XP, so that if you have a small picture, it'll stretch it to fit the whole desktop.
If this is the case, I'd suggest making the movie clip that the pictures get loaded into the exact same size as all of your pictures. That way, the pictures wont need to be stretched in any way.
Admittedly, I've never made a photo gallery in Flash, and so I'm not entirely sure how it works.