Adsl connection problems at startup

For the past week or so, I have been experiencing the following problem:

I have an adsl connection, which is not on all the time, but requires authentication each time I have to connect, like a dialup. I used to do that manually when I wanted to go online. For the last days, though, every time my pc (XP Home, p4 2,26GHz, password protected administrator account) stars up, it tries to connect to the Internet through the adsl connection. The problem is, it almost always fails to connect. and to make matters worse, when I right-click the connection, the 'connect' and 'status' options are greyed out! So, I'm stuck with a pc, that is unable to go online! I have to restart several times (and each time the same happens) until, by chance, the computer connects successsfully at some time, and I can use it.

I tried removing all startup items, in case they took up CPU power required for a successful connection, but nothing. I tried disconnecting before turning the pc off, so that it won't try to connect by default at the next startup, but it still does! How can I reset my pc to connect manually, and not try to connect automatically on every startup?

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