Manuscript was "unsubmitted" because the manuscript was deposited in Arxiv Preprints
Most journals now allow and even encourage the use of preprint servers. Some, however, still prohibit it on the notion that it is competition with their own publication of the article, or even consider it self-plagiarism. This tends to be field-dependent as well: some fields (e.g., physics, mathematics) are very liberal in policy, while others tend to be more retrogressive (e.g., chemistry, certain portions of biology).

The only way to tell a particular journal's policy, however, is to check the specific journal (the SHERPA/RoMEO database is also highly helpful, since it's easier to find the policies there and they have been pre-interpreted by experts).

If you have, indeed, been prohibited from submission due to a journal's policy on preprints, my only advice is to find another that allows it.