EMERGENCY: My laptop keeps shutting down randomly, how do I

[Jojoking]

I think i have a virus or hijacker or something in my computer as for the past few weeks every website i go on has the same advertisment whereever the advertisments are its for pills. Also when i search for something on like gooogle ect or anything and i click on something like a link it dosent bring up the right link half of the time. I have been trying to do a sytem restore to a point a few months ago when it was fine but when i first click on it nothing happens and so i go back in and click it again and then the window pops up but its comnpletely blank with the wee not reponding icon in the top left hand corner. I dont know what to do to make this work but i recently got nortons 360 on my laptop and ran scans and it removed threats ect but it still happens cant get restore and get thos adds and stuff. I Was told it may be a hijacker. I was wondering if it fixes and ridsit as it hasnt really done any good yet and i paid £60 for it and also how would i do it with it??? Any Ideas ***10 POINTS IF YOU CAN FIX IT**** iphone unlock