Hi,
It happened to me also and it caused by ESD.
Peter

Caisson wrote:

> Hello Pic-Listers,
>
>   Just now something strange happened to me, or rather to both 16C74A Pic's
> I've got here.  Before today they worked fine.  Programmed & erased them
> some
> times (about 2-3 times a day for 3 months, nothing special I think).  But
> suddenly
> my programmer (PicStart+) told me that my Pic's where not empty.  O.k I
> tought,
> lets erase them some more (50 minutes totally).  Nothing changed, they
> still
> where not totally erased.  O.k. , lets read and check them.  To my surprise
> the
> first 0400 hex bytes where fine, the rest (from 0400 up) were Zero's.
>
> eehhmmm...  That could be the Code-protect !  Let's check it ... No, its
> still Off,
> even after read-out of the Pic's memory.   Now I'm baffeled,  No
> Code-protect,
> Nothing strange in my program, but _BOTH_ my pic's showing this strange
> behavour.
>
> Anyone there who knows what happened here ?
>
> Greetz,
>    Rudy Wieser
>
> P.s.
> My question allready found his way to MicroChip (Holland) and they asked me
> toe send them the Pic's, cause the didn't know what could be wrong either
> ..