Well ... we arrived at a conclusion. One word. Ampersand.
Products with an ampersand in the title failed. Once we changed it to 'and' it went through fine. Now, what do we do to fix this? We have 499 products entered into our store and without checking them all individually is there any way we can fix this up? I'm guessing your response will be that you'll enter it onto your PS2 To-Do list?