How do I find out what the SBT for NIOS error "Downloading ELF Process Failed"?

Thank you all for your responses. I have tracked down the problem to the fact that I was using a copy of a Qsys system that was derived from a "Time Limited IP" Qsys system. I had removed the IP and renamed the Qsys, but there must have still been something in the Qsys that was causing the problem. I started from scratch and build a Qsys with the same features as Qsys that I had created by removing the "Time Limited IP" and it works like it should. However, it would have been nice to have a little more information about the problem than just the generic message "Downloading ELF process Failed".