dllhost.exe infected

[wings515]

I have been working on this laptop for over a week with no solution even after searching the web for every possible solution.
Here is what I have seen so far. When opening task manager and looking at processes from all users I see
dllhost.exe*32 using upwards of 80-90% cpu utilization and an ever increasing size of the file to over 100 MB. Many sites say dllhost is a system file and needs to be kept. I have 4 other PC's and all have this file at 0% and about 2-3M in size.
I have removed the drive from the laptop and reformatted the C drive, re-installed the OS from a CD. After doing the first round of updates all seemed OK. After the next round of updates the dllhost file again started to climb. Below are the steps I have tried.
I have run Avast (full Scan), Malwarebytes ( Full Scan) Combo Fix with no solution. I have changed permissions on dllhost and replaced it with a known good file. I watched the size of the replaced file and it started at 750KB and after a minute it started it's increase and the CPU utilization also climbed.
MS support wants $ to "fix" it. Most of the web based "fixers" scan and find all kinds of errors but none list dllhost.exe so I am reluctant to spend money not knowing if indeed they will correct the problem. On top of this, this is not my PC and the owner has already purchased a new Win 8.1 machine. I guess I am just a geek that would like to find the solution.
Thanks for any help.

 

[logicearth]

You are looking in the wrong place, dllhost.exe is fine. What you need to look at is what dllhost.exe is running.

Use Process Explorer: http://technet.microsoft.com/en-us/sysinternals/bb896653.aspx

 

[Tookeri]

Do you know it's caused by an infection or just guessing? Try scanning the file on https://www.virustotal.com/ it scans with 50+ different antivirus products.

Malwarebytes doesn't enable scanning for rootkits by default. You might try that as well.

There are a couple of suggestions here that are related to thumbnail cache problems:
Windows 7 dllhost.exe memory leak - Microsoft Community

 

[XpNiNjA]

dllhost never shuts the f&&& off always wants to connect to the internet to spy