GUI displays windows update error 0x80070005; c:\windows\windowsupdate.log snippet below.
Solution:
The c:\windows\softwaredistribution folder is corrupted (in this case was probably changed and then marked attrib +h +s by a virus). Stop windows update service & rename this folder, then run windows update "check for updates" from the gui.
Log snippet:
2014-08-16 14:32:26:990 5048 8c0 Misc =========== Logging initialized (build: 7.5.7601.17514, tz: -0700) ===========
2014-08-16 14:32:26:990 5048 8c0 Misc = Process: c:\Program Files\Microsoft Security Client\MpCmdRun.exe
2014-08-16 14:32:26:990 5048 8c0 Misc = Module: C:\Windows\system32\wuapi.dll
2014-08-16 14:32:26:990 5048 8c0 COMAPI -------------
2014-08-16 14:32:26:990 5048 8c0 COMAPI -- START -- COMAPI: Search [ClientId = Microsoft Security Essentials (EDB4FA23-53B8-4AFA-8C5D-99752CCA7094)]
2014-08-16 14:32:26:990 5048 8c0 COMAPI ---------
2014-08-16 14:32:26:990 316 1898 Agent *************
2014-08-16 14:32:26:990 5048 8c0 COMAPI <<-- SUBMITTED -- COMAPI: Search [ClientId = Microsoft Security Essentials (EDB4FA23-53B8-4AFA-8C5D-99752CCA7094)]
2014-08-16 14:32:26:990 316 1898 Agent ** START ** Agent: Finding updates [CallerId = Microsoft Security Essentials (EDB4FA23-53B8-4AFA-8C5D-99752CCA7094)]
2014-08-16 14:32:26:990 316 1898 Agent *********
2014-08-16 14:32:26:990 316 1898 Agent * Online = Yes; Ignore download priority = No
2014-08-16 14:32:26:990 316 1898 Agent * Criteria = "(IsInstalled = 0 and IsHidden = 0 and CategoryIDs contains '6b9e8b26-8f50-44b9-94c6-7846084383ec' and CategoryIDs contains 'e0789628-ce08-4437-be74-2495b842f43b')"
2014-08-16 14:32:26:990 316 1898 Agent * ServiceID = {7971F918-A847-4430-9279-4A52D1EFE18D} Third party service
2014-08-16 14:32:26:990 316 1898 Agent * Search Scope = {Machine}
2014-08-16 14:32:26:990 316 1898 Misc Validating signature for C:\Windows\SoftwareDistribution\WuRedir\9482F4B4-E343-43B6-B170-9A65BC822C77\muv4wuredir.cab:
2014-08-16 14:32:27:006 316 1898 Misc Microsoft signed: Yes
2014-08-16 14:32:27:224 316 1898 Misc Validating signature for C:\Windows\SoftwareDistribution\WuRedir\9482F4B4-E343-43B6-B170-9A65BC822C77\muv4wuredir.cab:
2014-08-16 14:32:27:240 316 1898 Misc Microsoft signed: Yes
2014-08-16 14:32:27:240 316 1898 Agent WARNING: Failed to obtain the authorization cab URLs, hr=0x80070005
2014-08-16 14:32:27:240 316 1898 Agent * WARNING: Online service registration/service ID resolution failed, hr=0x80070005
2014-08-16 14:32:27:287 316 1898 Agent * WARNING: Exit code = 0x80070005
2014-08-16 14:32:27:287 316 1898 Agent *********
2014-08-16 14:32:27:287 316 1898 Agent ** END ** Agent: Finding updates [CallerId = Microsoft Security Essentials (EDB4FA23-53B8-4AFA-8C5D-99752CCA7094)]
2014-08-16 14:32:27:287 316 1898 Agent *************
2014-08-16 14:32:27:287 316 1898 Agent WARNING: WU client failed Searching for update with error 0x80070005
2014-08-16 14:32:27:287 5048 1724 COMAPI >>-- RESUMED -- COMAPI: Search [ClientId = Microsoft Security Essentials (EDB4FA23-53B8-4AFA-8C5D-99752CCA7094)]
2014-08-16 14:32:27:287 5048 1724 COMAPI - Updates found = 0
2014-08-16 14:32:27:287 5048 1724 COMAPI - WARNING: Exit code = 0x00000000, Result code = 0x80070005
2014-08-16 14:32:27:287 5048 1724 COMAPI ---------
2014-08-16 14:32:27:287 5048 1724 COMAPI -- END -- COMAPI: Search [ClientId = Microsoft Security Essentials (EDB4FA23-53B8-4AFA-8C5D-99752CCA7094)]
2014-08-16 14:32:27:287 5048 1724 COMAPI -------------
2014-08-16 14:32:27:287 5048 884 COMAPI WARNING: Operation failed due to earlier error, hr=80070005
2014-08-16 14:32:27:287 5048 884 COMAPI FATAL: Unable to complete asynchronous search. (hr=80070005)
2014-08-16 14:32:32:287 316 1898 Report REPORT EVENT: {C8F6A7F7-41FA-4C5B-B471-9A030752F5B3} 2014-08-16 14:32:27:287-0700 1 148 101 {00000000-0000-0000-0000-000000000000} 0 80070005 Microsoft Security Essentials ( Failure Software Synchronization Windows Update Client failed to detect with error 0x80070005.
2014-08-16 14:32:32:287 316 1898 Report CWERReporter::HandleEvents - WER report upload completed with status 0x8
2014-08-16 14:32:32:287 316 1898 Report WER Report sent: 7.5.7601.17514 0x80070005 00000000-0000-0000-0000-000000000000 Scan 101 Unmanaged
2014-08-16 14:32:32:287 316 1898 Report CWERReporter finishing event handling. (00000000)
2014-08-16 14:32:34:579 2460 1010 Misc =========== Logging initialized (build: 7.5.7601.17514, tz: -0700) ===========
2014-08-16 14:32:34:579 2460 1010 Misc = Process: c:\Program Files\Microsoft Security Client\MpCmdRun.exe
2014-08-16 14:32:34:579 2460 1010 Misc = Module: C:\Windows\system32\wuapi.dll
2014-08-16 14:32:34:579 2460 1010 COMAPI -------------
2014-08-16 14:32:34:579 2460 1010 COMAPI -- START -- COMAPI: Search [ClientId = Microsoft Security Essentials (EDB4FA23-53B8-4AFA-8C5D-99752CCA7094)]
2014-08-16 14:32:34:579 2460 1010 COMAPI ---------
2014-08-16 14:32:34:579 2460 1010 COMAPI <<-- SUBMITTED -- COMAPI: Search [ClientId = Microsoft Security Essentials (EDB4FA23-53B8-4AFA-8C5D-99752CCA7094)]
2014-08-16 14:32:34:579 316 1898 Agent *************
2014-08-16 14:32:34:579 316 1898 Agent ** START ** Agent: Finding updates [CallerId = Microsoft Security Essentials (EDB4FA23-53B8-4AFA-8C5D-99752CCA7094)]
2014-08-16 14:32:34:579 316 1898 Agent *********
2014-08-16 14:32:34:579 316 1898 Agent * Online = Yes; Ignore download priority = No
2014-08-16 14:32:34:579 316 1898 Agent * Criteria = "(IsInstalled = 0 and IsHidden = 0 and CategoryIDs contains '6b9e8b26-8f50-44b9-94c6-7846084383ec' and CategoryIDs contains 'e0789628-ce08-4437-be74-2495b842f43b')"
2014-08-16 14:32:34:579 316 1898 Agent * ServiceID = {7971F918-A847-4430-9279-4A52D1EFE18D} Third party service
2014-08-16 14:32:34:579 316 1898 Agent * Search Scope = {Machine}
2014-08-16 14:32:34:595 316 1898 Misc Validating signature for C:\Windows\SoftwareDistribution\WuRedir\9482F4B4-E343-43B6-B170-9A65BC822C77\muv4wuredir.cab:
2014-08-16 14:32:34:595 316 1898 Misc Microsoft signed: Yes
2014-08-16 14:32:34:610 316 1898 Misc Validating signature for C:\Windows\SoftwareDistribution\WuRedir\9482F4B4-E343-43B6-B170-9A65BC822C77\muv4wuredir.cab:
2014-08-16 14:32:34:610 316 1898 Misc Microsoft signed: Yes
2014-08-16 14:32:34:626 316 1898 Agent WARNING: Failed to obtain the authorization cab URLs, hr=0x80070005
2014-08-16 14:32:34:626 316 1898 Agent * WARNING: Online service registration/service ID resolution failed, hr=0x80070005
2014-08-16 14:32:34:626 316 1898 Agent * WARNING: Exit code = 0x80070005
2014-08-16 14:32:34:626 316 1898 Agent *********
2014-08-16 14:32:34:626 316 1898 Agent ** END ** Agent: Finding updates [CallerId = Microsoft Security Essentials (EDB4FA23-53B8-4AFA-8C5D-99752CCA7094)]
2014-08-16 14:32:34:626 316 1898 Agent *************
2014-08-16 14:32:34:626 316 1898 Agent WARNING: WU client failed Searching for update with error 0x80070005
2014-08-16 14:32:34:626 2460 13d0 COMAPI >>-- RESUMED -- COMAPI: Search [ClientId = Microsoft Security Essentials (EDB4FA23-53B8-4AFA-8C5D-99752CCA7094)]
2014-08-16 14:32:34:626 2460 13d0 COMAPI - Updates found = 0
2014-08-16 14:32:34:626 2460 13d0 COMAPI - WARNING: Exit code = 0x00000000, Result code = 0x80070005
2014-08-16 14:32:34:626 2460 13d0 COMAPI ---------
2014-08-16 14:32:34:626 2460 13d0 COMAPI -- END -- COMAPI: Search [ClientId = Microsoft Security Essentials (EDB4FA23-53B8-4AFA-8C5D-99752CCA7094)]
2014-08-16 14:32:34:626 2460 13d0 COMAPI -------------
2014-08-16 14:32:34:626 2460 874 COMAPI WARNING: Operation failed due to earlier error, hr=80070005
2014-08-16 14:32:34:626 2460 874 COMAPI FATAL: Unable to complete asynchronous search. (hr=80070005)
2014-08-16 14:32:39:627 316 1898 Report REPORT EVENT: {6EF6C01E-A4B8-47D3-B3C5-1364DBC66B9D} 2014-08-16 14:32:34:626-0700 1 148 101 {00000000-0000-0000-0000-000000000000} 0 80070005 Microsoft Security Essentials ( Failure Software Synchronization Windows Update Client failed to detect with error 0x80070005.
2014-08-16 14:32:39:627 316 1898 Report CWERReporter::HandleEvents - WER report upload completed with status 0x8
2014-08-16 14:32:39:627 316 1898 Report WER Report sent: 7.5.7601.17514 0x80070005 00000000-0000-0000-0000-000000000000 Scan 101 Unmanaged
2014-08-16 14:32:39:627 316 1898 Report CWERReporter finishing event handling. (00000000)