You are not ready for immortality.

Explain?

Space filler operations stuck in infinite loops trigger out of memory crashes.

I think he/she might have meant that immortality isn't really sustainable because of overpopulation concerns unless population growth rate is negative.

Even if population growth rate is negative, that only means that birth rate minus death rate is negative, not that birth rate itself is negative. If immortality makes the death rate zero, the growth rate can't be negative, and the birth rate would have to also be zero or growth rate would become positive again.

True, and I wasn't necessarily advocating that point of view, only trying to clarify what the OP might have meant. However, I'd also add that immortality being an option doesn't necessarily mean that the death rate would become zero. Some people may opt to die or be unable to afford whatever the cost may be (not to mention homicide, accidental deaths, etc).

Also true. As you are saying, growth rate will remain non-zero birth rate minus non-zero death rate.