Here is the fix that got NextGEN thumbnails working properley for me in all browsers...
The problem is some code that is inside you style.css (or depending on your theme, whatever the .CSS is named as).
I always use FTP to manipulate CSS files not the WordPress editor, but thats my preference, its up to you to decide how you want to do it, but this is what you need to do...
First thing is to backup (save) your css file using a slightly different name, so if it is called style.css save it as style-ORIGINAL.css or whatever name you will recognise it as should you need to revert back to it.
Open your .css file to edit it and then look for the following code:
#content img, #content p img {
max-width: 100%;
}
Once you find this entry, you need to DELETE it, and then save the .css file using the name your WP will recognise it as, so in the above example style.css
That's it! You should now have your NextGEN thumnails looking exactly as they should do and not squashed up in all browsers.
I can only assume that IE looks at that code and does something whilst Firefox and Safari ignore the code.
Good Practice After A Code Snippet Change Like ThisDepending on what theme you are using, you may need to check that removing this snippet of code hasnt caused any un-wanted changes elsewhere, for me it hadn't but its wise to check whilst this modification is fresh in you mind what you have just changed.
I hope the above helps all those that have been banging their heads trying to work out what was causing the problem.
MattCarr
