Sounds like your computer needs a
real good clean out checking for and cleaning out any malware.
Malwarebytes is a handy free utility that sorts this sort of problem - here is the wiki page, which has a link to their home page:
https://en.wikipedia.org/wiki/Malwarebytes_(software)
The free one is something I use from time to time if I think somethings wrong that my AV has not caught.
Spybot is another one:
https://en.wikipedia.org/wiki/Spybot...ch_%26_Destroy
I also have used the free version occasionally - its a bit "clunkier" than Malwarebytes, especially for updating its definitions.
cheers
Andy