Free Avast may be one of the problems. Suggest you disable/ delete Firefox extensions mentioning such as Search protect or Avast.
Use the programs below to clean and remove adware.
Use CCleaner to remove Temporary files, program caches, cookies, logs, etc. Use the Default settings. No need to use the
Registry Cleaning Tool...risky. Pay close attention while installing and UNcheck offers of Google Chrome and Avast.
After install, open CCleaner and run by clicking on the Run Cleaner button in the bottom right corner.
CCleaner - PC Optimization and Cleaning - Free Download
Download AdwCleaner by Xplode onto your desktop. (compatible with Windows 7, 8 and 10)
- Close all open programs and internet browsers.
- Double click on adwcleaner.exe to run the tool.
- Click on Scan button.
- When the scan has finished click on Clean button.
- Your computer will be rebooted automatically. A text file will open after the restart.
- Please post the contents of that logfile with your next reply.
- You can find the logfile at C:\AdwCleaner[S1].txt as well.