Update errors: Code 800F081F and 0x80070002

I have Win7 SP1 64 bit. Windows Update Agent 7.6.7600.320 fails to install and now I can't get any Windows updates. I can install other updates if I download the standalone update files from Microsoft's website, just not the Update Agent. When Windows Update tries to update to the WU Agent 7.6.7600.320 I get the 800F081F error. I downloaded the standalone update file (from Update to...