OS X :: Very Frustrating Confusing Internet?

i have a 2wire 2701HG-B that I used to use on a windows via ethernet cable but I have this new imac so ive been goin wireless. unfortunately, i haven't been that successful.the internet sporadically goes out very often for a few minutes to twenty minutes all the time, daily. I would say that 50%-70% of the time I try to use the internet I can not. looking at the router, usually all the lights are green regardless of whether or not the internet is working, sometimes (like right now) the DSL light will flash red. When the light is red, the internet does not work but unfortunately the internet also does not work when the light is green.

a typical example:
If I am searching the web and go from one site to another (say from macrumors to gmail) I will get an error, usually "problem loading page" and that will happen for any new site I try to load. But, if I went back to macrumors in that same tab, I can use the site like normal. If I selected to open something in a new tab, the tab would give me the "problem loading page" yet if i clicked on the link in the original tab, it would load just fine.of course sometimes the internet goes out in all tabs, on all applications as well.I called ATT and they said they couldnt find any problems, then I called the local ATT to see if they were having problems and they weren't. they did offer to come down and be sure my chord is plugged in correctly for a fee.