We got Denny's PC to work for a short time by changing his DNS settings. If those settings have not changed, I am at a loss for suggestions for a solution.

My paranoia leads me to think that one possibility is that Verizon DSL is as devious as Time Warner Cable (and Google) regarding their "use policy/agreement" (in the massive fine print). Verizon might have poorly maintained DNS servers and Verizon might not want its users to bypass their DNS servers (they are able to thwart/stop this). Why? Verizon might be selling information regarding the types of places that users are visiting (Google does this, as do other DNS services). I apologize for wasting you reading-time with this complicated and paranoid conjecture.