That's weird, I thought it showed up on Add/Remove programs for me. Then again, I had an ATI graphics card. Are you using an Nvidia card? If so, PhysX may be rolled into your graphics drivers. You could try uninstalling your graphics drivers, installing Two Worlds (and letting Two Worlds install PhysX for you) and then reinstall your graphics drivers.

Clearly, you will want to be careful if you try that. Does anyone know of way to uninstall PhysX without removing all the Nvidia drivers?

Driver Sweeper has a setting for removing Physx.

You could also check the registry suggestion in the last post of this thread

Thanks for the ideas and links. I am getting a copy of Driver Sweeper and am keeping the link to the registry post. And, yes, I do have an NIVIDA card, which apparently has the PhysX welded to the driver.

What I did last night was get angry enough to run System Restore, picking April 10 as far enough back. The graphics driver reverted to 186.18 from the 270.XX version, and the PhysX became 909.04.28. This gave the error message on the first start of the game, but played just fine and on reopening the game, no error msg, just went ahead and played. Not the technical solution or elegant, but since my problem was an unplanned upgrade of the NVIDA driver, solved it for me. Plus my saved game reappeared...