Wow, PICStartPlus, there's a blast from the past, haven't used mine for probably 10 years.

Did you read the other thread I linked to?
The problem occurs when you're using internal MCLR AND internal oscillator. But there's plenty to read on the subject so I won't go into details here.

If you can use external MCLR that's the easiest way to get around the problem, it's not recommended to use R/C network on the MCLR pin, a simple pullup is enough in 99% of the cases.

/Henrik.