Thanks Melanie but I have tried all the above. I have about 100 of the TI chips and none work. I also tired the pullup resistor changes too.

I have tried comparing the data sheets and find no real differences. I also tried the Picbasic commmands for slowing the clock even though I am using a 4 mHz rock.

Tried the obvious - now I am looking for something hidden.

Larryt