Restore the OS per Dell's instructions and it should be as good as new if there is no hardware issue.
I just bought a used dell inspiron n7110. When I hook up to my wifi I get full bars, but the internet takes forever to load. When I first got it, I thought it was because I had netflix going, and another laptop running. Turned the other one off and it ran okay then went slow again?
So, I know it's not my wifi. Anyone know what would cause this? Not sure if this is the right place to post this or not?