System Interrupts Using Around 20-25% of CPU

December 27, 2011 at 10:26:53
Specs: Windows 7 Ultimate N SP1 64-bit, Intel i5-2400 3.1GHz / 4GB RAM
I first noticed this problem a month ago, but it went away when I restarted, so I didn't worry about it. However, yesterday and today, the same thing happened, so now I'm worried.

When I start up my computer, Windows will take extra long to start. I'm not talking ten minutes or anything crazy like that, but it's definitely longer than normal. When it finally does start, there is noticeable lag and choppiness when I drag my mouse across the screen. Also, the Windows start up sound is also very choppy. For all three times that it's happened so far, restarting the computer has fixed the problem, but I'm asking here to make sure this doesn't become a regular occurrence.

This morning when it happened, I looked in the Task Manager, and I can provide the following details:
-CPU usage fluctuates between 20-40%
-Physical memory usage is 25%
-No applications running
-No processes in the list show CPU usage greater than 01

However, when I dig into the Resource Monitor, it shows that System Interrupts are responsible for 20-25% of CPU usage.

I started up HWMonitor, but nothing was out of the ordinary. All temperatures were fine.

I'm not sure what to think about this problem, because for the past month, I haven't installed anything new or done anything different. Also, why would a simple restart fix the problem?

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December 27, 2011 at 10:35:58
This sounds like you might have a root virus..

Open the Task Manager if you can and sort the processes from highest usage to smallest and repeat the top ten on here please.

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December 27, 2011 at 10:41:22
When I open up the Processes tab in the Task Manager, all the processes are under 01. That was really baffling to me, but opening up the Resource Monitor showed that it was System Interrupts that was responsible for the bulk of the CPU usage. Is there a chance that a system scan by McAfee would find out if I had this root virus?

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December 27, 2011 at 10:51:59
Root viruses are often very hard to detect.. and they are not technically classified as "viruses" but more like trojans.

In this case, go to and download Spybot - Search and Destroy, update the program and run it. After its done, reboot.

Lemme know how it goes!

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Related Solutions

January 5, 2012 at 17:36:38
I tried what you suggested with SpyBot, but the problem persists. As you requested earlier, here is a list of the top ten processes by usage:
1. System Idle Process (97)
2. taskmgr.exe (01)
3. dwm.exe (01)
4. svchost.exe (01)
5. System (01)
6. WmiPrvSE.exe (00)
7. svchost.exe (00)
8. svchost.exe (00)
9. mcagent.exe (00)
10. VDeck.exe (00)

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January 5, 2012 at 20:15:15
You can download Process Explorer from Microsoft since it shows processes better than Task Manager and helps you identify even the 'svchost' ones.
You will probably find that McAfee is the culprit here, possibly after a recent update. It probably loads right after the core system components and is scanning everything as it loads. My recommendation is to uninstall McAfee and go with Avast, Webroot, or MS Security Essentials instead. If you want to experiment with turning McAfee off to verify this, I would say scan with Malwarebytes first and then physically unplug from the internet and any networked hardware before doing it.

You have to be a little bit crazy to keep you from going insane.

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January 6, 2012 at 07:51:04
If it's what I think it is, it is using the svchost.exe

The three svchost.exe processes.. what does the "Description" say for each of them?

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January 6, 2012 at 08:06:16
The description for all of them is 'Host Proc...', but the User Name for one of them is 'SYSTEM' and the other two are 'LOCAL...' Sorry for the ..., I'm going off a screenshot I took of my screen.

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January 6, 2012 at 08:16:01
If it's host processes, I don't really think that's anything to worry about.

Another idea I have is to maybe disable some programs you have on startup.. maybe that's participating to the problem, too many programs trying to access the internet and updates at the same time. Click Start and in "Search Programs and Files", type in msconfig

One of those tabs is labeled "Startup", these are all of the programs that start with your computer each time you boot it up. For the programs that don't need to start with it, uncheck it on the left (i.e. Adobe Reader, Adobe ARM, Microsoft Office, etc). Once your done with that, it will prompt you to restart your computer.

Also, how much hard drive space do you have left?

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