Shockwave Player is apparently abandoned by Adobe for Windows now, but I've uninstalled the Java, Adobe Air, and Flash Player and will install them again.
Let's hope this help.
Edit:
Reinstalled Java, Flash Player, Adobe Air, and ran Windows Update that had been asking me to restart the computer for a couple of days.
Double clicked the game's execution file. And nothing...
This game is the only one - from trying several update versions - that has not started when I've tried playing it, all the other .jar game files I try work perfectly...