28034 Programme Jump in "ILLEGAL_ISR" trap

Hello everybody:

          I'm from shanghai China.I use TI's 28034 chip.Now I meet a strange phenomena "My programe will jump in trap of "ILLEGAL_ISR". I want your help.

         My programe is simply like below:

       void main()

{

InitSysCtrl();     

   MemCopy(&RamfuncsLoadStart, &RamfuncsLoadEnd, &RamfuncsRunStart);

   InitFlash(); 

   init hard_interface();

  init interrupt();

 other_proc();

for{;;}

{

     cycle_a();

     cycle_b();

}

interrupt_proc()

{

     interrupt_a();

     interrupt_b();

}

}

  Now  my  programe in  init step it will jump in "ILLEGAL_ISR" trap. AND it awlays occured before "other_proc();"mark     .But when i add "asm( " nop");" in the programe everywhere,just like on the top of void main ,before init interrupt();,even in for cycle,in interrupt_proc(), mark      If i do this ,the programme will return to normal.

  I wonder the condition of jump in "ILLEGAL_ISR" trap.I haven't found the data sheet about this!

 Looking forward to your answer!

Best regard to you!

                                                                                                                    FengXianGuo

                                                                                                                    Sep. 27th  2010