Hi Haribabu,

I think, there is a watchdog inside the P89C51RD2. Maybe, there is some code, which enable the watchdog.
Also on some micro the watchdog can be enabled during programming the Flash.

Please watch, the AT89C52 can run at 24MHz, but the P89C51RD2 only at 20MHz, if the clock doubler (crystal / 6) was enabled.

Also have you checked, that the power was clean ?


Peter