The upgrade to 18.0.3 took less than 2 minutes, once I finished downloading the installer. It went fine.
I ran the program and tried to make a chart; same error. So it was time to replace that little library module.
I did NOT have to use the Terminal to change anything; the Finder worked fine, once I opened the SPSS package ("Show Package Contents") and looked in the lib file that the SPSS support e-mail told me to look for.
The file is named "libspssjvm.dylib", which presumably stands for "Library SPSS Java Virtual Machine DY Library" (whatever the heck DY stands for.... grin...). The procedure is exactly what you would expect: rename the original (in case something goes wrong), put the new file into the folder where the old one was, close everything up, and you're done.
I did this, and now the problem is fixed; I can make charts (presumably using Java) anywhere in the program.
Why they couldn't integrate this libspssjvm library update into the update program, I don't know.
Good luck, everybody! Open a support ticket, get your libspssjvm.dylib, and go to town!
To get your copy, you'll need to register with SPSS Support, which will request your serial number. Just run SPSS, then from the Apple menu choose "About PASW Statistics". The serial number is in a box there. Mine is 8 digits long.