Hi Dave,

According to the datasheet, the number of erase/write cycles this chip can take is 100,000. So this cannot be as to why you are seeing the error.
Can you check if the MCLR pin goes to about 13v on clicking the program button without the chip in the programmer ?

There are three common reasons as to why you could get the error:
1) Damaged serial cable
2) Damaged PIC
3) The PIC was programmed the first time selecting Internal Oscillator with MCLR pin function disable.

The third one may be the one causing the trouble for you.

Also, write protecting a chip will not prevent it from erasing and re-writing.
Just to eliminate any programmer faults, you can try with a new (never programmed before) chip.
If this works, then your programmer does not provide VPP before VDD during programming.