I bought this desktop from a Future Shop in Surrey, I think, back in 2009 and it was working fine mostly except for the times that I screwed with it and had to take to a Future Shop (before it is sold) and Best Buy, at least two times. It's a Gateway machine with a big HP monitor.
There were numerous unknown (to me) issues with the machine. I was not even able to update the maps of my Garmin GPS. And then one day adds started popping up in the middle of a website or the machine would kick me out of YAHOO when I was sighed in to read my e-mail.
The first thing I did was downloading, installing and using a sort of software which had been introduced to me by The Brave. Since he's a cheap guy always trying to pay as less as possible, that didn't quite worked! Then I bought a new version ESET NOD anti-virus. I don't even remember when I had bought or downloaded the older version but I paid some $20 and upgraded the system. That helped a bit but not with the popping adds.
The final solution was to reset the computer back to factory setting and I did that! Now the system is fine. I bet the Best Buy guy did the same thing. I have all of my files intact and the system works with no problem at all. You should try the same if your problem's similar to mine. The system is still good after 8 years although not many people use desktops these days. I do have a laptop which I bought in last Jan. and that's wonderful. I will have a separate post for that.
(Photo: One of the Future Shops in Calgary, on MacLeod Tr. shortly after being closed down permanently. This store was actually new. They just had moved from two or three block north of this location! Mr. Hassan Khosroshahi, the Iranian investor, sold Future Shop to Best Buy in 2015)