I've had this error a while and I keep looking but can't find a solution.

Problems: - Every time I start my computer it 'Cannot connect to system event notification service'. This means non admin users cant log in and I guess a number of other issues I'm unaware of.
- My CPU performance according to Task Mgr is always 100%. THis can't be right. (Although not in safe mode)
- Also seems to have defaulted my taskbar to Windows classic. And I cant seem to change it back to Aero.

Attempted Solutions: - So far I've installed malwarebytes/spybot and antivirus(avast). - I've done a system restore to before the time it started.

I'm totally stumped. I think either its a complex virus, I've missed something obvious or its a Windows Update or something.

Currently running Windows 7 (home premium). Any advice would be great!

  • possible duplicate of Computer is infected by a virus or a malware, what do I do now? – bwDraco Apr 14 '12 at 23:11
  • Please do the following three things: 1) Use the task manager to see which task is using 100% CPU. (Add that information to the post). 2). Check the eventmanager for error (start, run, eventvwr.msc). If there are obvious errors, add then to the post. 3) Dragonlord alreaxdy linked to the anti-virus post. One key point in it is not to boot from a suspect system in order to clean it. Use one of the liveCD methods. – Hennes Sep 9 '13 at 7:20

I had the same saturation problem on my HP Pavilion DV6 and found this answer that worked perfectly for me..

Windows 7 100% CPU usage on H-P Dv6

Anyone experiencing maxed CPU usage by "search protocol host" and/or "permon", "indexing" on a H-P laptop, I suggest returning "Power Management" to "HP Recommended". It seems to cause some "loop" or conflict in the HP software. It is a simple fix, drove me crazy for weeks. But I have since duplicated the 100% cpu usage by another (foolish) attempt to manually manage the power settings. Hope this helps some of you.


What process in task manager is using all the CPU cycles?

Or, open a run command and type in


this will open a resource monitor, you can see what is hogging cpu cycles.

  • According to resmon PresentationFontCache.exe is using 75-80% of my CPU. FontCache3.0.0.0 is also using 50-65% of my services. – whatup Apr 10 '11 at 16:07
  • i found this which is a temporary solution i think. doesnt seem like the best thing to do.. social.msdn.microsoft.com/Forums/en/wpf/thread/… – whatup Apr 10 '11 at 16:16
  • Sounds like the font cache was corrupted. Looks like a proper fix to me, be sure to re-enable the Service. – Moab Apr 10 '11 at 16:39
  • 1
    When in doubt, back up important data and reinstall clean, sometimes damage done by malware is hard to correct. – Moab Apr 11 '11 at 14:40
  • 1
    Aye. Easier, and safer. Never trust a seemingly cleaned laptop with your important data. E.g. never use it for on-line shopping (amazon etc), internet banking, ..., .... Make a backup of all important data. Do a clean reinstallation and make sure all updates are installed. Then scan your backupped data before restoring it. – Hennes Sep 9 '13 at 7:25
  1. Download Spy-bot from download.com
  2. Check your computer for virus.
  3. Go to Start Menu type services in the search box.
  4. Click Properties on UPnP Device Host and disable start up.

Second option is searching system configuration on the Start Menu, start up sisabling all start up the start up items or if it's still not working then change your battery.

  • 2
    How can this be related to batteries or the UPnP service? – Marcks Thomas Mar 24 '13 at 18:34

protected by Community Sep 9 '13 at 8:48

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