It appears that at 0000h you have no JMP instruction that causes the MCU to jump over your interrupt vectors and to the beginning of the program.

In your code, you have nothing at 0000h. Instead, the MCU will immediately execute your timer 0 interrupt at 000Bh even though a timer interrupt has not ocurred.

Insert an LJMP to the beginning of your code at ORG 0000h.

Craig steiner