I've been experiencing an ongoing issue on my laptop for some time but had been tolerating the high cpu drain from svchost.exe and cooling fan working overtime. Recently I decided I'd return the laptop to its factory state and hopefully cure the problem but have discovered that if I turn off Windows updates the problem goes away. It also transpires that apart from new virus definitions for Microsoft Security Essentials my laptop has not recieved any updates since July last year, the last being KB3079904 which was installed on 23.7.2015. If I turn on updates and tell it to seach for new updates it appears to be searching but nothing is found and it just keeps searching indefinitely while svchost.exe resumes taking 25/30% cpu which causes the fan to atart working overtime again. When I turn off updates and restart the machine all is good, apart from having a severely un-updated system.
I've read that this behaviour may well be a result of Microsoft trying to encourage Windows 7 users to migrate to Windows 10 which is something I'd prefer to avoid. If that's the case I guess a factory reset won't make any difference so I need to try fixing my updates before deciding how to proceed further.
So far I've tried the relevant steps given at https://www.winhelp.us/reinstall-windows-update.html and manually searching and installing update KB3145739 which seemed to help similar issues detailed at http://www.bleepingcomputer.com/forums/t/611172/windows-update/ but to no avail. I'm still left with high cpu use, a racing fan and no updates. I tried isolating the service causing the svchost.exe cpu drain according to the instructions given at https://blogs.technet.microsoft.com/askperf/2009/04/10/prf-high-cpu-svchost-exe/ but the resulting message in the command prompt screen was ''OpenService failed 5: Access is denied''.
Using Sysinternals Process Explorer I also see there are several processes with the comment ''Error opening process'' or ''The system cannot find the file specified'' showing in the path column. These processes are smss.exe, csrss.exe, wininit.exe, sevices.exe, WmiPrvSE.exe, dllhost.exe, audiodg.exe, Seaport.exe, WLIDSVC.EXE, WLIDSVCM.EXE, CVHSVC.EXE, an instance of svchost.exe, HpSupportSolutionsFrameworkService.exe, IAStorDatamgrSvc.exe, lsm.exe, another instance of csrss.exe, winlogon.exe, GoogleCrashHandler.exe, Google CrashHandler64.exe and SynTPHelper.exe. I don't know whether these are related to the update issue or evidence of some other problem I need to address but it doesn't look good.
Any advice on how to proceed with further diagnosis and repair will be most appreciated.