FreeRtos on LPC2387

I have been able to run the FreeRTOS demo ARM7_LPC2368_Rowleywebserver on the LPC2368 processor with no problem. When I run it on the LPC2387, I get no Ethernet when running at 72Mhz and lots of missed packets when running at 48MHz. 36 Mhz runs fine. I tried the MCFG clock configuration, but that does not help. Has anyone else had this problem? Any suggestions? Also same results with LWIP+FreeRTOS.