Pop Ups

Ok, so in January I purchased a new computer from Dell. For the first month or so it was the greatest thing in the world. I finally had my very own computer. I didn't have to use my roommates or go to the library. It's my own. Then probably two months into ownership the computer starts going completly fricking crazy on me. So annoying. First it got some virus. Then I wound having to spend hours into the night on the phone with Dell representatives to reformat my computer. Two days after I had the whole thing reformatted another virus hits. Followed by two more that week. Now for some reason its just now starting to run ok. The only thing left that ticks me off is the damn pop ups. I can't get rid of them. Just drives me crazy.