Reading from the DM9000A at 100 MHz

hi,

i am trying to read data from the DM9000A (on the DE2 evaluation board) to the NIOS II, which is easy at 50 MHz but i have since overclocked to 100 MHz. writing to the DM9000A seems to be working normally, i.e. i can transmit packets from the NIOS without trouble, but reading from these registers does not seem to be giving me valid data, i can only assume these problems are related to the clock speed?

has anyone used the DM9000A at a speed higher than 50 MHz or have any ideas? (to clarify...i am clocking the DM9000A at 25 MHz, but the IORD calls are clocking at 100 MHz)