Unhandled program error after closing with Crtl+Alt+Del

[Dr. J Foerster]

I finally managed to reproduce your issue here as well.
As far as I can tell it is a Windows issue: By "killing" the program through the Taskmanager Windows is not correctly informed about the status of temporary files. The operating system still considers theses files as being in use (while they aren't), so generating a new file with the same name will give the mentioned error.

A workaround I noticed does always work here is to start Ple4Win after a "kill" not by double-clicking your project file, but by double-clicking the Ple4Win desktop item. In other words, start Ple4Win without a project. Then open your project through the file menu, the last used project can be found at the top of the list with recently used projects.

I am not sure we can do a lot about the current behaviour, "killing" a program is always risky and very often has unwanted side effects...