Monster Rancher and HD Loader

[symptom]

The HD Loader compatibility list website (I forget the address) states that both Monster Rancher 3 and 4 work fine, but I have encountered some trouble with the monster generation system and cannot find any other info on this topic. I tried running Monster Rancher 3 off of a hard drive with HD Loader and all went well until I tried to generate a monster from CD at the beginning of the game. The game said the disc tray would eject, but it never did so I ejected it myself and inserted the disc -- nothing happened, the game remained frozen.

Is there any way to get Monster Rancher to run off the hard drive while maintaining the ability to generate monsters from disc?

I have a version 7 NTSC PS2 w/ Duo2SE.