yes, I figured out that McAfee was on the machine (new HP desktop installed an unwanted McAfee). I did not notice until I installed XAMPP and tried to run mysql. When mysql did not start I got serious about looking for crapware, and found McAfee. Uninstalled that, and then reinstalled XAMPP, which then ran fine, and then ran Phidgets control panel,and allowed it to try to update to 1.6.2xxxx, which was successful.
Whee! My phidgets tasks are running now.
Might be worth noting in the Windows instructions that an AV program might interfere with the installer. I wonder why 1.5xxx install was not blocked?