Fuse mystery with a Duemilanove/ATmega328P

Development Tools IDE 1.x
5

I can otherwise flash the unit with new programs and so on.

Flash this then:

#include <avr/boot.h>

#define SIGRD 5

void setup ()
{
Serial.begin (115200);
Serial.println ();

Serial.println ("Signature");

byte sig;
  sig = boot_signature_byte_get (0);
  Serial.println (sig, HEX);
  sig = boot_signature_byte_get (2);
  Serial.println (sig, HEX);
  sig = boot_signature_byte_get (4);
  Serial.println (sig, HEX);

Serial.println ("Fuses");
byte fuse;
  
  fuse = boot_lock_fuse_bits_get (GET_LOW_FUSE_BITS);
  Serial.println (fuse, HEX);
  fuse = boot_lock_fuse_bits_get (GET_HIGH_FUSE_BITS);
  Serial.println (fuse, HEX);
  fuse = boot_lock_fuse_bits_get (GET_EXTENDED_FUSE_BITS);
  Serial.println (fuse, HEX);
  fuse = boot_lock_fuse_bits_get (GET_LOCK_BITS);
  Serial.println (fuse, HEX);
}

void loop () {}

That self-detects the fuses and displays them.