Error 0x80004002

You see the following errors in "%Windir%\WindowsUpdate.log".

FATAL: Failed to get session from datastore, error = 0x80004002
FATAL: Failed to Unserialize from data store, error = 0x80004002
WARNING: Exit code = 0x80004002
WARNING: InitAUComponents Failed, will restart AU in 30 mins, error = 0x80004002
DnldMgr FATAL: DM:CAgentDownloadManager::CheckAllCallDownloadStates: GetSession failed with 0x80004002.

1. If you have a proxy server -

Stop Automatic Update Service - "Net stop wuauserv".
Run the following command: "proxycfg.exe -u".
Start Automatic Update Service - "Net start wuauserv".
Force update detection and see if that works.
2. Re-create the Datastore -

Stop Automatic Update Service - "Net stop wuauserv".
Rename/delete "%Windir%\SoftwareDistribution" folder.
Start Automatic Update Service - "Net start wuauserv".
Force update detection and see if that works.
3. Try to force install WUA.

Download WUA WindowsUpdateAgent20-x86.exe from http://go.microsoft.com/fwlink/?LinkId=43264.
and run the following command: "WindowsUpdateAgent20-x86.exe /wuforce".