When I upload a photo, I then look at my list to see if it's there. If not, I check the "confirm" box and delete it.
I think the problem has to do with file names. Imbedded spaces cause problems and I also suspect that you can't have two files with the same name, even if they are not in the same folder.
The posting board software may be written fail safe between operating systems.
Read the wiki on file naming conventions to get some idea how nasty this can be.
http://en.wikipedia.org/wiki/Filename
