Unwanted tabs in Google Chrome

I have Google as my default search engine. However I have recently found "MyStart" and "yahoo" search engines in tabs behind my normal Google search. I have constantly removed "MyStart" and "Yahoo" from  Google Chrome Settings > On Start Up > Open a specific page or set of pages > Set pages > Start Up Pages and reset Google,but they return the next time I open Google chrome. I have also reset Settings > Search > Manage Search Engines and reset Google as default Search engine. I have reset browser settings to default with no luck.

The AdwCleaner log is below

# AdwCleaner v3.016 - Report created 05/01/2014 at 18:00:51
# Updated 23/12/2013 by Xplode
# Operating System : Windows 7 Home Premium Service Pack 1 (64 bits)
# Username : David - PAULANDHONEY
# Running from : C:\Users\David\Desktop\Torrents\Downloads\adwcleaner.exe
# Option : Clean

***** [ Services ] *****


***** [ Files / Folders ] *****

File Deleted : C:\Windows\System32\Tasks\NCH Software

***** [ Shortcuts ] *****


***** [ Registry ] *****


***** [ Browsers ] *****

-\\ Internet Explorer v9.0.8112.16526


-\\ Mozilla Firefox v23.0.1 (en-US)

[ File : C:\Users\David\AppData\Roaming\Mozilla\Firefox\Profiles\jwokp6qg.default\prefs.js ]


-\\ Google Chrome v31.0.1650.63

[ File : C:\Users\David\AppData\Local\Google\Chrome\User Data\Default\preferences ]

Deleted : urls_to_restore_on_startup

[ File : C:\Users\Liz\AppData\Local\Google\Chrome\User Data\Default\preferences ]


*************************

AdwCleaner[R0].txt - [12849 octets] - [04/01/2014 11:45:30]
AdwCleaner[R1].txt - [1219 octets] - [04/01/2014 14:13:38]
AdwCleaner[R2].txt - [1339 octets] - [05/01/2014 17:49:38]
AdwCleaner[S0].txt - [12792 octets] - [04/01/2014 11:48:05]
AdwCleaner[S1].txt - [1284 octets] - [04/01/2014 14:18:14]
AdwCleaner[S2].txt - [1264 octets] - [05/01/2014 18:00:51]

########## EOF - C:\AdwCleaner\AdwCleaner[S2].txt - [1324 octets] ##########

Any help with removing these unwanted tabs would be appreciated. thanks.

Hello and welcome to GeekPolice.Net My name is Dave. I will be helping you out with your particular problem on your computer.

1. I will be working on your Malware issues. This may or may not solve other issues you have with your machine.
2. The fixes are specific to your problem and should only be used for this issue on this machine.
3. If you don't know or understand something, please don't hesitate to ask.
4. Please DO NOT run any other tools or scans while I am helping you.
5. It is important that you reply to this thread. Do not start a new topic.
6. Your security programs may give warnings for some of the tools I will ask you to use. Be assured, any links I give are safe.
7. Absence of symptoms does not mean that everything is clear.

If you can't access the internet with your infected computer you will have to download and transfer any programs to the computer you're using now and transfer them to the infected computer with a CD-RW or a USB storage device. I prefer a CD because a storage device can get infected. If you use a storage device hold the shift key down while inserting the USB storage device for about 10 secs. You will also have to transfer the logs you receive back to the good computer using the same method until we can get the computer back on-line.
*************************************************************************
Please download Malwarebytes Anti-Malware from here.
Double Click mbam-setup.exe to install the application.

• Make sure a checkmark is placed next to Update Malwarebytes' Anti-Malware and Launch Malwarebytes Anti-Malware, then click Finish.
  
• If an update is found, it will download and install the latest version.
  
• Once the program has loaded, select "Perform Full Scan", then click Scan.
  
• The scan may take some time to finish,so please be patient.
  
• When the scan is complete, click OK, then Show Results to view the results.
  
• Make sure that everything is checked, and click Remove Selected.
  
• When disinfection is completed, a log will open in Notepad and you may be prompted to Restart. (See Extra Note)
  
• Please save the log to a location you will remember.
  
• The log is automatically saved by MBAM and can be viewed by clicking the Logs tab in MBAM.
  
• Copy and paste the entire report in your next reply.
  

Extra Note:

If MBAM encounters a file that is difficult to remove,you will be presented with 1 of 2 prompts,click OK to either and let MBAM proceed with the disinfection process. If asked to restart the computer, please do so immediately.
*************************************************
Please download Junkware Removal Tool to your desktop.

•Warning! Once the scan is complete JRT will shut down your browser with NO warning.

•Shut down your protection software now to avoid potential conflicts.

•Temporarily disable your Antivirus and any Antispyware real time protection before performing a scan. Click this link to see a list of security programs that should be disabled and how to disable them.

•Run the tool by double-clicking it. If you are using Windows Vista or Windows 7, right-click JRT and select Run as Administrator

•The tool will open and start scanning your system.

•Please be patient as this can take a while to complete depending on your system's specifications.

•On completion, a log (JRT.txt) is saved to your desktop and will automatically open.

•Copy and Paste the JRT.txt log into your next message.
*****************************************
Download Security Check by screen317 from one of the following links and save it to your desktop.

Link 1
Link 2

* Double-click Security Check.bat
* Follow the on-screen instructions inside of the black box.
* A Notepad document should open automatically called checkup.txt
* Post the contents of that document in your next reply.

Note: If a security program requests permission from dig.exe to access the Internet, allow it to do so.