Ken,
Here is what is happening behind the scenes: with any modern digital picture, there are various "metadata" tags that can indicate when the picture was shot, what the camera settings were, even the GPS coordinates if the device is set up that way. One of these tags is rotation -- how the device was rotated when the picture was taken. Generally, when you work with a digital picture on a computer or hand-held device, the pixel data is never changed; the computer or device just reads the metadata tags and adjusts for the current conditions (screen size, rotation) "on the fly."
The exception to the general rule is with forum software -- most forum software does actually reduces the size (resolution) of the pixel data when it is uploaded; in the process, I believe most forum software reads the rotation tag, and as needed actually re-orients the stored pixels to the proper rotation. This allows the web software to store the picture without using up so much room (not only reduced size, but also all metadata tags stripped out); it also helps speed things up a tiny bit to send out the picture data without having to manipulate it -- it is already sized appropriately for most screens, and already rotated to the proper orientation.
This forum is an exception to the general rule for forum software! This one does not automatically reduce the size of uploaded pictures; it stores the whole file you send, however big it may be. I'm not sure if that's why this forum seems to have more trouble with the rotation issue, though I have noticed that Apple products seem to cause trouble in this respect for many forums. Since this forum doesn't do it automatically, it is a very good idea to reduce the size of the picture before uploading -- otherwise, for folks with slower connections, it can take a long time for the pictures to download. Actually, for any forum, even ones that do automatically reduce the size, I always re-size before uploading, just so it takes less time to upload.
But here's the catch: Just about any computer/device software that reduces the size of a digital picture will NOT re-orient the pixels; it just reduces the size, leaving the rotation tag in the metadata, and counts on the displaying device to take care of rotating as needed. And here's a bigger catch: even if you manually apply a rotation, trying to correct for the problem, most software still doesn't actually re-orient the pixels; it just adjusts the metadata tag! So you need software that can re-size and re-orient the pixel data physically, without regard to the metadata.
For this and other picture-manipulation purposes, I use a suite of programs called imagemagick -- this is on a Linux machine, but the same thing is available for Macs and I believe for Windows. Unfortunately, these are command-line programs, so you have to be willing to "geek it" to use them. I guess one of these days I need to write a little GUI wrapper around this program that would allow folks to deal with this issue more easily ...
