When you first get a new sat-nav, it's not unusual to go around gathering custom POIs and 'going a bit mad' with them. I assume that these things are held in RAM, and that there must be a finite capacity. With several thousand speed cameras alone, is there a sensible limit to other custom POIs? My machine crashed yesterday, shortly after being given a route to calculate. Then I got rid of some of the more frivolous POIs (J D Wetherspoon's Pubs!), and all has been well since.
Sorry, there appears to be no way of predicting a crash. The best thing to do is to install a large microSD card (up to 16 GB) and to keep the extras on it. The internal memory is less than 2 GB and thats full pretty quickly. I haven't had any crashes on my 1350T since I installed the big microSD and put all my POIs, JPEGs and extra maps on it