My aunt had a pressure-cooker story, one of those family stories that get told and retold for years. She was cooking beans in the pressure cooker one day, when something got clogged. Pressure built up until the lid was blown off the cooker, and beans were blasted clear up to the ceiling, where they stuck and had to be cleaned off with considerable effort.
I'm older and wiser now, and I shudder to think that that hot lid could have hit somebody in the family. And burns from steam are terrible.
Richard, your pressure cooker is old and unreliable. Replace it.