welcome to the forum.
i suggest a boot scan, and send the files to the chest.
http://www.schmahl.net/avastbootscan.php
and do a scan with malwarebytes anitmalware to get a second opion.
http://www.filehippo.com/download_malwarebytes_anti_malware/
download install update a do a scan and don’t forget to remove what it finds. a system reboot might be necassary.
good luck and let us know on the progress or if you need more support.