Error message when you use Windows Update or Microsoft Update Web sites to install updates: 0x80070424
http://support.microsoft.com/kb/968002/
If no joy, click the Start orb, in the Start Search field type in
cmd
Right click cmd.exe and choose 'Run as administer'. Follow the prompts to allow the Command Prompt to run.
At the prompt, type in the below and press Enter after *each* command
regsvr32 wuaueng.dll
exit
Restart the system and see if it can update now.