Possible DMA/Avalon bug?

I have been trying to get my uClinux MMC Driver working with DMA. I added a DMA controller between my DRAM and the MMC Core (just an SPI Core). Now, for some reason, whenever I try to write to any registers in the SPI Core, the system locks up. This is with DMA disabled, so I haven't even touched the DMA Registers yet.

Has anyone experienced this with DMA and SPI? I'm using Quartus II 5.1 SP2 and Nios II 5.1 SP 1.