Problem with serial interrupt

Hi Shyam,

While dealing with the serial interupt i am facing a different kind of problem.

this is serial interrupt program , my logic is ,

when i give some data through serial port , program counter should goes to serial interrupt routine and process something(Here am transmitting data in wireless)......

the probelem am facing here is,

when i give data serially ,program counter get into Serial ISR
ReceiveDataReady(RDR) Flag is Set
U1IIR is 4

but when executing the first instruction(what ever it may be)
for instance checking (RDR) Flag
everything gets vanished means (RDR becomes 0 and U1IIR becomes 1)

I Couldnt process the interrupt...........

For Your Reference i have attached the Serial Port initialisation and Serial ISR