I've patched the forum, you can now upload much larger images and the forum should automatically resize your image, without messing up the page.
I've limited the size of the images that can be uploaded, although I've been very liberal.The size limit is 3MB, which will seriously slow down the pages for some users on slow connections. I encourage you to manually resize your images to decrease their size before uploading. If I feel some pages are running too slowly then I might have to reduce those size limits. For now though lets see how it goes.
I welcome any feedback.
Thanks
Rob