error connecting to broadband.

hi, i had a quick look around but couldnt find any help.

i'm using vista basic, desktop pc, everything is connected up corectly.

Everything was working perfectly until the other night, i turned the computer on and my modem always has green lights but the internet light was red. I tried to diagnose and repair the problem, and a box popped up sayin that windows could not repair the problem automaticly and that it was a problem with the DNS, so i contacted talktalk but they only told me what i already know. Anyway, the light is now flashing green on the modem but sometimes i have problems loading up pages and quiet often a dial-up connection box pops up asking me to connect, but when i click connect another box pops up offering me a choice to redial, cancel or diagnose with a messege mentioning an error 815 and mentioning something about some invalid values for the service name fields for the connection.

really hope somebody can help me.

Thanks
Jon