Avast Antivirus 2015 R2 is the only avast software that is windows ten compatible
It sounds like it may not be recognized as a virus, and maybe is running as a background process
In safemode: Please look in your running processes and services to see if there is anything that you do not recognize, do not disable any processes that work directly with your OS or you will have a bigger problem.
Go into you programs and see if there is anying installed that shouldnt be. Disable any startup programs that are not neccessary.
Delete all current virus software and download malwarebytes or avira. I prefer avira because it does more for you. Get spybot search and destroy 2.0 After checking your computer manually run these software(without internet connection)
If all else fails run a system restore and restore to a previous time in which you didnt have an issue
Make sure you back up all documents and photos so you dont lose anything.
In the windows 10 install screen, i went to the cmd prompt, deleted all partitions, formatted my hdds and then changed them to GPT partition tables, restarted, then allowed the windows 10 installation to remake all partitions and it installed successfully.