I am revisiting my PointerDetective tool, which relies heavily on ProtoObject>>pointersTo. The example I recorded at the repository home page is currently locking & crashing the image due to #pointersTo being unable to handle the circular reference. This "must" have been working on Windows at least around August 2014, but I've been unable to reproduce a working case since my Windows laptop died and I've since moved to OSX. On OSX, in a fresh image 40467 and latest vm 402, the following crashes the image... testObject := 'TEST'. ref1 := { testObject. nil }. ref2 := { ref1 }. ref3 := { ref2 }. ref1 at: 2 put: ref3. "note the reference loop this creates" testObject pointersTo inspect. OSX Memory Monitor shows memory usage shoot from 50MB to >500MB in a few seconds, then usually the image crashes, but sometimes just hangs. I've logged... https://pharo.fogbugz.com/default.asp?14827 cheers -ben