OK, I've also found that Limewire is automatically changing the "Listen on" port, even when I set it manually. This is causing conflicts with my firewall and my direct port forwarding settings on my router. When I try to change back to the original port, it tells me that it is not available.
Any idea what this means?

Try using port 64049. Make sure both your listening port & manual port forward box have the same port. Also within your router.

What port were you using for Morpheus?

When files download slowly from magnetmix, it often points to an ISP problem. Of course, I can't say for sure that it's Platinum's fault & I'm not trying to pass the buck & say it's nothing to do with the LW setup