if the SSP completely stops working after loading a WAV file in the granular, perhaps there is something about the file that trips up the WAV reading code. If that happens please post the properties of the file such as sample rate, number of channels, bit resolution, file size, WAV format header etc. If the file is not too big then post the file as well, if you can.
The granular does not have “safety features” buit-in, as @Mark describes, so it’s up to you to manage the parameters yourself, such as number of grains, level of the grains and so on. So this is not a bug but rather a feature.