Addendum:
Last weekend, I installed the available Ubuntu software updates that were presented, as usual. When they were complete, iStripper would no longer run--definitely NOT as usual. Uh-oh.
To make a long story short, after a week of troubleshooting, repeatedly re-installing iStripper, Wine, and Ubuntu itself, and debugging with no resolution, I finally came upon the answer: the OpenGL driver had been updated to a version that has a bug that makes it incompatible with older graphics cards. I'm running this on a positively geriatric Dell Optiplex with the onboard Intel graphics chip.
It was surprising that even re-installing the OS would not correct this; it must have been grabbing the latest OpenGL driver during the install. The good news is that there is a simple fix.
If iStripper crashes at launch and your Wine log shows an error that says GLXBadFBConfig, then try editing ~/.pam_environment (create it if it isn't present):
MESA_GL_VERSION_OVERRIDE=4.5
Also, another lesson learned: ALWAYS TAKE A SNAPSHOT OF YOUR SYSTEM BEFORE ALLOWING A SOFTWARE UPDATE.
I repeat: ALWAYS TAKE A SNAPSHOT OF YOUR SYSTEM BEFORE ALLOWING A SOFTWARE UPDATE.
If I had done this, I easily could have reverted back to the previous snapshot and saved myself a lot of grief. Timeshift is a great tool for taking whole system snapshots on a schedule or on demand.