Windows update failure: WindowsUpdate_800705B4

Hi everyone. I've recently run into some problems with Windows Update that I've never seen before. I've been running Windows 7 Professional x64 since the RTM (months now), and I've never had an update failure.

Recently, I've had two. Both have happened during an update to Windows Defender definitions. They've been of this variety: "WindowsUpdate_800705B4"

I think the updates download just fine, but they just stall out before they install.

If I try to manually re-run the installation after the failure, they install with success. But seeing Windows update throw up a big red X makes me NERVOUS. What will happen one day when it's an important OS update rather than defender definitions, and it destroys my computer utterly?

The only programs I've added recently are WinPatrol 2010 and Sandboxie, but I've not set up either in such a way as to interfere with Windows update.

Thanks for any help!

1.Read this article Windows Update error 800705b4
2.The second:You may encounter temporary connection-related errors when you use Windows Update or Microsoft Update to install updates