We too had this problem in our square hopper; we were hoping the 5 gallon bucket would fix it. Though we haven't gotten it mounted yet, I really hope it does.
How is your problem manifesting? Are the discs falling over the back or sliding out the front when you put them in? For us, we found they slid out the front as we threw the first one in and the second one slid over the back of that. From then on out we were screwed because our pusher came from the back and pushed the second disc, now angled back over the first and pushed them both bound together into the top wall of our hopper, thus not getting them out. Our hope was that a round hopper would index them so they could not angle over eachother.
A few other solutions we are still pursuing include little 'spurs' found in a
CD thread earlier this year that spin around over the discs and separate the discs. We also considered an electric solenoid that would lock the discs in place so they didn't fall out the front as well as some brushes to form a 'door'. Finally, we're upping the power on our rotary pusher from a VEX 393 to a Banebots 550 in a 64:1 that we just happened to have lying around to motor through any binding after the angle issues are worked out.
To BurkeHalderman, could you explain your angled piece a bit more? I don't see how it works on your robot.