Filter on my internet connection

I bought a refurbished computer from Geeks, it is a Dell Optiplex 745 and it has a filter from Apache Product an it is stopping me from getting on AOL and most of yahoo. Called geeks they were no help. When I open AOL this is what it said. Status:513 misconfigured proxy route cache-control: no-cache pragma: no-cache connection: close content-type: text/html**. This computer I think was in some Co. My internet is from a Verizon wireless card, my dell laptop works just fine. Hope you can help.