USB Trouble on my G5


Ok so here's the deal. I got g5, with a bit of usb gear to put into it. My keyboard has a usb mouse and dongle attached to it, and that's connected to of the usb ports in the back.
I've also got a music keyboard (edirol pcr50) that I had to plug into the front port, becasue if I plug it into the other one in the back the mouse freezes. Just the mouse. I REALY hate having the usb for my music keyboard out front. . .I think it looks lame.
So does anyone know of how I can fix this? I just tried a usb hub and that didn't work either.
Thank you,