What options are given when this window appears? You say it says "Select the service". Does this list other connection options?
It sounds like your PC is attempting to connect on Startup.
If so, goto Start > All Programs > Startup and see what is in there. If there is a copy of the DUN (Dialup Network) in there delete it.
If not, goto Start > Run, type in msconfig and click OK. Check in the Startup tab for anything that is trying to connect on Startup and de-select it.
Mark
I have dial-up service on my Windows XP computer. I like to decide whether I connect to the internet or not. Every time I turn my computer on a screen immediately pops up stating "Select the service you want to connect to, and then enter your user name and password". This screen is annoying to me. I have to close this sceen each time. I have my internet provider's icon on my desktop and I don't want this screen showing up. How can I stop this screen from showing up? Thank you very much. user429

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