What is the maximum size of a GIF image that Internet Explorer can render?

It seems that Internet Explorer has a fixed limit on how large (dimensions, not file size) of a GIF it can render. If a GIF is under this limit, the image appears correctly. If the image is larger than the limit, you see that lovely red-X rather than the image. The box that contains the X matches the dimensions of the image, and if you right-click and select properties the image properties specify the correct file location and dimensions for the image.

The interesting thing is that it doesn't appear to be a fixed limit for height/width, or even the area of the image, but a combination of both the area and the height/width.

Does anyone know what the limit is for the size of a GIF image in IE 5/6

If you'd like to see for yourself the limit that I'm referring to, create a 1x1 black pixel in your favourite image editor, and save it as a GIF. Open this image in IE and it should display correctly.

Resize the image to 3000*3000 pixels and the image should display.
Resize the image to 3800*3800 and the image won't display.

Resize the image to 3800*3449 and it will display.
Resize the image to 3449*3800 and it will not display.
Resize the image to 3800*3450 and it will not display.

Resize the image to 10,000*1310 and the image will display.
Resize the image to 10,000*1311 and the image won't display.

Resize the image to 100,000*380 and the image will display.
Resize the image to 100,000*381 and the image will display.

I originally thought that it was something to do with the height/width of the image, but as you can see, the image that is 100,000 pixels wide will display, while and image that is 3800 pixels wide might not. I then thought that it was the area of the image, but that doesn't seem to be correct either. Some images will or will not display regardless of the area. In one of the above cases, the image will/will not display if you simply reverse the dimensions (3449*3800 fails, but 3800*3449 works).

I've tried this with a few versions of IE 5 and 6. I've used three different image editing applications to generate the images (Visio, irfanview, and something else that I tried last year), and I've tried in WinXP and WinXP SP2. It seems to work pretty consistently.