Lpc2000

I am using a lpc2214 with the ASHling development kit. When I enable 
UART1 to work with interrupts, I seem to be losing the top 3 bits of 
the byte I am transmitting. (loopback is enabled ). For example, if I 
send 0x2f, I get 0x0f in my receive buffer. 

Could anyone please help me with this issue. I have been fighting it 
for about 8 days now with no success.