It sounds like you have a problem, in that something has been installed and now has control of the machine. Probably won't do any damage initially but will eventually by inviting lotsa nasties in. Messages will apear requesting money for evil stuff to be fixed - if you cough up, it won't get fiexed, messages will just go away and nasties will still be invited in.
See if you can download a copy of Malwarebytes - it usually fixes this, but not always.
Sorted out several of these recently.
If you meed any more info etc, PM me with details of nasty.
I posted without looking at Uncle's suggestion