50% CPU with no apps running. Process is dllhost.exe.

I am running Vista Home Premium.

Every now and then, I notice that my CPU is running at 50% capacity, with no
apps running. Task Manager reveals the culprit as dllhost.exe. I kill the
process and everything is fine.

Virus scans are current (McAfee).

How do I tell what dllhost is running on behalf of?

What legitimate functions will I prohibit if I disable dllhost.exe? What
is the easiest way to do that?

- David

Why don't you google dllhost.exe? That's what most people who try to answer
your question will have done first.

"David D." <daviddiamond.removeifnotspam@comcast.net> wrote in message
news:fMydnd_lEYWE7IrVnZ2dnUVZ_siknZ2d@comcast.com. ..
> I am running Vista Home Premium.
>
> Every now and then, I notice that my CPU is running at 50% capacity, with
> no apps running. Task Manager reveals the culprit as dllhost.exe. I
> kill the process and everything is fine.
>
> Virus scans are current (McAfee).
>
> How do I tell what dllhost is running on behalf of?
>
> What legitimate functions will I prohibit if I disable dllhost.exe? What
> is the easiest way to do that?
>
> - David
>

Well, I guess if I ask a general question, I should expect a general answer.

So let me try to frame my question better.

I do do a lot of Googling before I post. On the subject of dllhost.exe, I
have not found the specific information that I am looking for. (That does
not mean that it is not out there; there is a ton of information on
dllhost.exe).

There are offers of free registry scanners to ferret out dllhost.exe
problems, and that those free offers might themselves be spyware.

There are snippets of registry entries that are supposed to help, but they
are from untrusted sources.

What I do know is that dllhost.exe runs COM/COM+ objects, and that it has
legitimate uses by the OS and by COM-based applications. I also know that
it should only exist in the \windows\system32 directory. That doesn't mean
that a virus, trojan or spyware might not be using the legitimate
dllhost.exe, or might even have replaced the legitimate version there.

Also, just because a DLL is used by the OS, that does not mean that it is
running an OS function that is necessary to my own small subset of
applications. I am not running IIS. I am not aware of running any
applications are COM based.

Whatever process is running dllhost.exe at 50% CPU on my computer is
non-critical, because I can kill it with no ill-effects.

What I have *not* been able to discern in my web research is *which*
critical OS functions use dllhost.exe on a home computer running Vista Home
Premium, and *how to determine*, while it is running, what processes,
services or applications dllhost.exe is running on behalf of, or is
executing. What are my potential diagnostic tools here?

That is why I am posting my question on a Microsoft newsgroup. I assume
that this newsgroup is monitored by MS developers, who have some inside
scoop.

Any guidance would be greatly appreciated.

- David D.

----- Original Message -----
From: "David P" <dgprozzo@bellsouth.net>
Newsgroups: microsoft.public.windows.vista.performance_mainten ance
Sent: Tuesday, April 29, 2008 4:41 PM
Subject: Re: 50% CPU with no apps running. Process is dllhost.exe.
> Why don't you google dllhost.exe? That's what most people who try to
> answer your question will have done first.

> "David D." <daviddiamond.removeifnotspam@comcast.net> wrote in message
> news:fMydnd_lEYWE7IrVnZ2dnUVZ_siknZ2d@comcast.com. ..
>> I am running Vista Home Premium.
>>
>> Every now and then, I notice that my CPU is running at 50% capacity, with
>> no apps running. Task Manager reveals the culprit as dllhost.exe. I
>> kill the process and everything is fine.
>>
>> Virus scans are current (McAfee).
>>
>> How do I tell what dllhost is running on behalf of?
>>
>> What legitimate functions will I prohibit if I disable dllhost.exe?
>> What is the easiest way to do that?
>>
>> - David D.
>>

David D. explained :
> What I have *not* been able to discern in my web research is *which* critical
> OS functions use dllhost.exe on a home computer running Vista Home Premium,
> and *how to determine*, while it is running, what processes, services or
> applications dllhost.exe is running on behalf of, or is executing. What are
> my potential diagnostic tools here?

Try this one:
http://technet.microsoft.com/en-us/s.../bb896653.aspx

--


Kind regards,
Mark Veldhuis.

Thank you, Mark,

This looks like an excellent tool. I will use it next time my
dllhost.exe phenomenon occurs.

I suspect that my dllhost.exe activity may have to do with system startup
or logon processing, but I haven't logged it to see if that is consistently
when I am seeing the problem or not.

I will see if I can pin it down.

- David D.

"Mark Veldhuis" <me@privacy.net> wrote in message
news:mn.f4bc7d843156e046.85949@privacy.net...
> David D. explained :
>> What I have *not* been able to discern in my web research is *which*
>> critical OS functions use dllhost.exe on a home computer running Vista
>> Home Premium, and *how to determine*, while it is running, what
>> processes, services or applications dllhost.exe is running on behalf of,
>> or is executing. What are my potential diagnostic tools here?
>
> Try this one:
> http://technet.microsoft.com/en-us/s.../bb896653.aspx
>
> --
>
>
> Kind regards,
> Mark Veldhuis.
>
>