We have had large images in the gallery thumbnails before as well as thumbnails that only loaded half way. They did not corrupt the IE browser, but they did make it harder to view the gallery. Most of the resons for those files are how they were saved too such as punctuation in the filename, cmyk vs rgb and long file names. In the past Doug has corrected potential problems himself, but as this site grows it's harder to keep up. The ideal solution is for users to submit them in accordance with the following:
Things To Remember When Saving An Image for the Web
1. Make sure the image is in RGB mode vs. CMYK
2. PhotoShop users save your images using the "save for web" feature
3. When naming your file, don't use punctuation, or mile long names.
4. Don't embed extra data in your files such as slices.
Thanks In Advance For Your Cooperation!