Speculation, since I don't have the relevant software: - the Windows icon cache is dependent on the display configuration (in particular, bit depth, and maybe

Speculation, since I don't have the relevant software: - the Windows icon cache is dependent on the display configuration (in particular, bit depth, and maybe pixel density) - unplugging a monitor therefore flushes the icon cache - the relevant file is an explorer icon overlay handler (which is identified by the registry key one needs to mitigate the problem) - therefore flushing the icon cache causes a mass refresh - the handler is probably looking to see if some True Image process is running † - maybe it needs that to show different icon overlays? - it's probably also doing that for every icon (i.e. the caching isn't happening across different icons, at least when the cache is flushed) † in hind sight, this is better done via a named pipe or mutex or something (Edit: added line breaks)