[kraegar]

Just to check - you haven't run any new electrical cable (new wall outlets, new lights, whatever) lately, or installed any new flourescent bulbs in /on/near where the cable that goes to your DSL modem runs, have you?

I've seen a couple times where people have installed a new electrical outlet, and it's caused interference that resulted in issues like you're describing. (If you do have to cross an electrical cable, do it at right angles. Never run a data line parallel to an electrical cable unless it's very shielded)