Hello,
I don't know how, but my CarpetIOHDF5 problem has seemed to have solved itself, and I can now access my results, so I haven't opened a ticket on your website.
To Hal, I also didn't have any problem whilst only using 1 processor on my supercomputer.
To Erik, I use Visit to view my results, and I was getting an error saying it could not open it, and claiming it was an invalid file. We managed to open up one of the files, but only gibberish was saved in it.
Thanks for your help anyway.