I was notified I have an important update to download but, when I try to d/load it gets half way across the bar and no further.
I have tried a few times but its the same.
If so move the main windows on the desktop and see if there is a window underneath waiting for you to select on it.
I had this happen today, the Windows update window sat there for agwes doing nothing and when I moved it to one side there was another smaller window underneath
The update is corrupt dont try to install it . To prevent it reappearing hide it until Microsoft can repair it. This is happening at present in 64 bit Windows 7 updates . Dont download it and try to install it manually either as it will cause you grief as well Microsoft are aware of this and are working to repair it.