Looks like I've tracked this down via the Windows Reliability Monitor. Turns out there was an AdAware DLL file causing the trouble. (Years ago, AdAware was a recommended app, but apparently it's pretty much malware now.) Malwarebytes AdwCleaner got that cleaned out and the current Poser update now starts without crashing.

Thanks for your help, everyone.

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Hardware: AMD Ryzen 9 3900X/MSI MAG570 Tomahawk X570/Zotac Geforce GTX 1650 Super 4GB/32GB OLOy RAM

Software: Windows 10 Professional/Poser Pro 11/Photoshop/Postworkshop 3