update Overtaken by OP's additional info in thread above. NO <strike>...</strike> as the observation may tickle a neuron in another monk, someday.
Given BrowserUK 's yeoman attempts to help you, you might consider that the known, common factor on all five machines is the code you wrote. That, it seems to me, makes it worthwhile to check that code carefully... and to be sure what you showing in your OP is still relevant.

In reply to Re^7: Behavior of threads on XP-- system() works, backtic & popen don't... by ww
in thread Behavior of threads on XP-- system() works, backtic & popen don't... by Sync

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