Strange Problem when uploading images

[mayo23]

I have a problem uploading some of my images. I have created more than one image for some of the products, and I seem to have a problem uploading some of them - but not all.

When I do have a problem with an image upload, it returns an error;

1. an error occurred while copying image.

However, the strange part is that the error also seems to move the product into another category!!

I have compared the different images and the ones that fail are no bigger in pixel or file size than those that are succeeding.

I have also increased all the relevant settings in my php.ini file to allow more memory usage and higher script time outs.

Any one had the same problem, or can anyone suggest a potential area to investigate?