Perhaps one day in life I'll actually have something useful to say, but probably not today.
When they finally improved the resolution for uploading photos, my first complaint was that when you open it, it doesn't automatically resize the image to fit your screen. So yes, having to horizontally scroll is a problem for everyone. That's what I was getting at with right-clicking. For instance, in Chrome, if you right-click on the image and say open in new tab, then the browser will resize the image to fit your window. I was wondering if that made it look more like the image you were expecting to see. It's still not too awesome looking, but better than looking at the blown up image.
But I guess looking your photo, you'r using an Olympus 720SW 7 megapixel camera, yet the size of your image, as you note is only 663 KB, which is way too small if you're shooting at 7 megapixels and way too small for a 2048 x 1536 image.
So something is going wrong in the steps from download it from your camera to computer and uploading it from your computer to mountainbuzz. Given other photos, I don't think it's mountainbuzz compressing it that much. It almost seems to me like you've got a small dimension photo and it's uploading it and thinking it's a larger dimension, but I don't know how that would happen.
Take a look at the EXIF data of the file you have on your computer (on Windows you ought to be able to right-click, properties, and look at the Details tab). What are the dimensions & size in there? If those look normal, maybe trying resizing it yourself to something smaller, like a 1200 pixel long end with minimal compression and then upload it.
That's all I got.