I tried using the following background changer for Pharo (from http://book.pharo-project.org/book/CustomizingPharo/PuttingABackgroundPictur...). All was well and it nicely changed the background image to various images from socwall.com. I walked away and when I came back, Pharo was no longer running. To make a long story short, on Linux and OS X (I did not try Windows), after some period of time, regardless of whether I am actively using Pharo, Pharo either hangs (becomes unresponsive to input, using 100% CPU, images no longer changing) or disappears abruptly. I tried several variations of the script, including loading images from a local directory (i.e. no network code at all) and even loading images into an ImagePreview morph. In all cases, Pharo eventually either aborts or hangs. I have found nothing in the logs to indicate what happened -- no entries at the time of the abort or hang at all. Decreasing the delay seems to make it happen sooner; I can usually make it happen within 15 minutes of execution with a 2 second delay. It seems to happen more quickly when changing the background image than in an ImagePreview morph. I monitored Pharo's memory usage and it increased from 106 MB to 109 MB during the execution. Plenty of free memory on the system. My questions are: 1. How to debug this? Log to a file to see where it is hanging? 2. How to regain control of a hung Pharo. I tried Cmd-<everything> to no avail. 3. Does anyone have any idea what might be happening? Some resource being used up, a race condition, etc.? Here's the original script [[[ | rx str url form | str := (HTTPSocket httpGet: 'http://www.socwall.com/browse/index.php?wpLimit=1&wpSortby=8') contents. rx := '.*(http\://.+tb_.+\.jpg).*' asRegex. url := (rx matches: str) ifTrue: str := (rx subexpression: 2) copyWithRegex: 'tb_' matchesReplacedWith: '' ] ifFalse: [ nil ]. url ifNotNil: [ form := ImageReadWriter formFromStream: (HTTPSocket httpGet: url). World backgroundImage: form layout: #scaled]] on: Error do: [:ex| ]. 1 minute asDelay wait ] repeat ] newProcess name: 'Random background changer'; priority: Processor userBackgroundPriority; resume Regards, TF