humm well the images are less then 2mb (and i think the hosting could be set to 2mb) ..so that full under the limit...however i did take a look at the folder via FTP and noticed that there are temp images uploaded from the unsuccessful upload and their seem to be in pairs...with the second being [random alpha-numeric name]TMP.jpg so the files seem to be uploaded...just in pairs...if you were to add the total file size of both pairs together then would exceed the 2mb limit (they are 1166kb each)...this is the only logical explanation i can think off because file seems to be uploaded (just in a temp state).
Chris