Since I built this computer in 2010 I've had a scheduled task which runs a VBS script to remind me to take my tablets each morning. Until the last few days, only one element was visible from this task, the message box spawned by the VBS script.
However, in the last few days, I also get a taskeng.exe window appearing at exactly the same time as the message box. The window is labelled taskeng.exe, has a VBS scripting host icon and the content of the window is pure black.
If I terminate taskeng.exe in Task Manager or click OK in the VBS message box, both the VBS script and that black window disappear.
I have no idea what might have caused taskeng.exe to only appear in this situation, because MSI AfterBurner also uses it to start the app during user login and it doesn't appear for that. Both processes are ones I've been using for ages longer than this problem.