What were you incoming amounts like?  1-10 PRT at a time kind of thing?  If so then you have the common large transaction error that affect many coins particularily if you mine at a p2pool that routinely sends you small amounts (see a couple pages back for more detailed info).  Short story you will likely need to run the --salvagewallet command to recover the stuck sent transaction and try again with a smaller amount.  When the wallet indicates that a transaction fee is needed, I use that as a warning and find that it is best to cancel and try a smaller amount rather than attempt to send and have it get stuck.