Windows complete pc backup generates a window where the system suggests where
to store the backup. This window is shown in the nexus dock, but only with icon, not with contents as normal program windows.
Further, when peeking any other window the special window is not redrawn, only the title bar is to be seen. I guess, for both phenomens there is the same reason: Nexus can't draw the window content of this special system window.

Nexus 11.6, vista u 32 bit, w7 hp 64 bit

I don't want topics with unrelated issues mixed in, as that becomes messy quickly, so I've split your message from the other topic.

Although I haven't tested it yet, it's possible that the Complete PC backup window is a layered window. As such, no content image can be formed of it for dock icons because the bitmap that holds the image of that window is held in the private process space of the Complete PC backup application.

This should not affect the live previews in any way, just the 'static' thumbnail icons in the dock.

Anyway, it seems like the Windows Complete PC Backup has been changed considerably in Windows 7 in relation to Vista.