Ok, either updating the video driver or the act of rebooting afterwards seems to have solved the problem... thanks! On the installer, it looks like the new one will only work if the most recent Poser you installed on your system was P6 (and maybe P6 SR1). I had recently tried re-installing P4 to fix a problem with that, so when I tried P6 SR2, it didn't initially find my P6 (and manually pointing to it with the dialog didn;t help). Re-installing P6 SR1 let the Sr2 installation proceed.

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