OK a new data point. I have an upgraded from Win7 pro copy of Win10 (which I don't like and don't use) which is probably at a patch level at least a year or more old. It didn't ever have Fritzing on it, so I just installed the 64 bit zip file. Starting Fritzing I got the "we need to delete these files to do the parts update" which I approved, it then did the parts update and closed Fritzing. When I restarted fritzing and clicked the search hourglass and search comes up and works as expected. So search does work on Win10. I'll leave the machine alone for a while (I have several 
) to do updates and see if an update kills it. Note Old_Grey's post just before this that deleting the directories has worked for other people in the past although someone here tried that without success, I still think that is the most liekly cause of this. I may try loading a part that I know hangs fritzing and see if that breaks it as well a bit later as well if patches don't break it (I can see traffic on my adsl modem probably indicating the other machine is loading patches ).
Peter