hello world - strange variables behavior

Hello,

I'm new to nios2 developpement and i'm having problems running the simple hello_world exemple :

When I lauch this code :

int main()
{
  unsigned char i,j,k;
  printf("Hello from Nios II!\n");
  while(1){
      i++;
      j++;
      k++;
      if(k==100){
       printf("a"); 
      }
  }
  return 0;
}

in the debugger, i can see that the 'i' variable is incrementing correctly, but the 'j' variable always have the value 203 and the 'k'variable always have the value 0.

Although i cant see the 'k' value changing, the program does go in the if statement.

Could anyone explain to me why i cant monitor correctly the variables values?

Thanks

ps: running this program, i also have an other problem regarding the console ouput as described in this post : alteraforum.com/forum/showthread.php?t=27499. I supposed it could be related