I am observing the following phenomena:

I do have installed KB2511290 on my computers (productive and test devices). Nevertheless I cannot upload drivers via iManager to our driverstore without being prompted that KB2511290 would be missing.

I (re-)installed this KB repeatedly with no effect.

KB2546651 (sometimes needed as well) is "not applicable for my computer" according to Windows.

After a lot of tries to (re-)register the printui.dll (with a lot of errors/not working) I came to the following workaround:
Run the IE (a pity that Firefox ESR 17 is not supported...) as administrator! This lets the IE/Windows/iManager recognize the installed KB2511290 - I am not prompted anymore.

Is there an explanation for these phenomena?