What is the meaning of the subclause of 'goes off the deep end'?

Question

If a real-time program **goes off the deep end**, the system can become unresponsive.

Answer 1

It is used much in the same way the similar phrase "in over their head" is - the implication is that the subject in question is in a situation that is beyond its ability, just as a poor swimmer who is in deep water could be at risk.