OK, two things:
1) to post a picture simply make it a jpeg - I find that 640 on the longest side and medium quality works just fine for size. Then attach the file using the "manage attachments" button when you scroll down a little when you write a message. It will then bring up a screen that allows you to browse for the file, select the file and click UPLOAD NOW. Once it is uploaded correctly it will have the file listed in blue...you can then finish with that window which returns you to your message screen and from there you simply click on submit or post or whatever it says...
2) I had something that sounds quite similar. It was a card/memory error. I reformatted the card and have never had any trouble again. It showed only on some pictures taken over two dives, luckily, but there didn't seem to be any reason for those to have it and others not.
Don't know if you can reformat your card or if the camera is all internal memory...might be worth a look, though.
If you can get those photos posted we can help a lot more - maybe!