Unreal Editor freezes at launch (but I can hover over items and icons)

when launching Unreal Editor, my computer freezes after everything has loaded.
I can hover over icons and assets (it shows hints, definitions and such) but I can’t do anything in the editor (nor my OS (win7 x86-64) with the exception of Task Manager) but it all works after again after I kill the UE4Editor.exe process.

it all worked smoothly a couple of months ago, no freezes, no crashes, nothing.

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