This article is related to this warning.
After a few very intensive days of searching, I managed - with the great help of the Wing Helper Beta Test Team and 3 further users who ran into the same problem - to pinpoint the reason for this problem and find a way around it.
It turned out, that antivirus programs going by the names AVG and AVAST (they are practically the same product) are causing Wing Helper to crash reproducibly in the "File Open" and "File Save" dialogs. All "historical" fixes for this problem, which are circulating in internet discussion forums, like not using the native file dialogs, did not work for me.
Uninstalling AVG and AVAST works reliably - Wing Helper instantly springs back to life!
This behavior does not affect Wing Helper in virtualized Windows (tested with VMWare).
I am sorry for any inconvenience this might cause you!