MCB 2300 blocked

i have changed the PLL setting in the start up code as per the below listing.

PLL Constants original value changed value
PLLCFG_Val EQU 0x0000000B 0x00010027
CCLKCFG_Val EQU 0x00000004 0x00000007 USBCLKCFG_Val EQU 0x00000005 0x0000000A

in this case the FCCO value is 288 MHz in previous case and i have changed it to 480MHz and cclk i have changed to 60 Mhz from 57.6 MHz ( as in user manual it is mentioned that 480MHz is the minimum possible value for Fcco if u want to use both USB and UART)

and the main loop code is

int delay;
PINSEL4&=0XFFFFFF00;
FIO2MASK=0XFFFFFF00;
FIO2DIR0=0XFF; while(1) { FIO2SET|=0X000000FF; // OFF LED's for(delay=0X00FFFFFF; delay--;); FIO2CLR|=0X00000000; // ON LED's }

after downloading the code the JTAG was not able to enter into the debugging session. when i have checked for the Debug device chain window i found that there is no Device ID .

i have tried with flash magic to erase the controller by using a serial cable ( with jumpers J4 and J13 removed ) when i tried to read the devise signature it was not able to read and hence i was not able to erase the controller either.

please try to suggest me what is the root cause of the problem. what is the problem with the pll settings? i have not changed any thing in pll settings appart from changing of the 3 constants( as specifeid on top) in the startup code generated by the KIEL Uv3.