Hi there,
My advice is to confirm your Internet password, this can easily by asking your ISP to verify that it is correct.
Next, in Internet Options, delete the entry in the password field and make sure the save password box is not checked.
ClickApply then OK.
Now, depending on which version of Windows you are using, locate and open Dialup Networking (in either My Computer(98), Control Panel (2000 & ME & XP)). Right click on your ISP icon, select Proerties and delete the password entry from there also, once again making sure that Save Password is unchecked. Click OK.
You should now be able to connect by double clicking the ISP icon, entering your password and clicking connect.
P.S. If you normally connect via your ISP icon shortcut on your desktop, you will need to delete this and recreate it.
To delete, right click on it and select delete.
To recreate, right click on the one still present in Dialup Networking and select Create Shortcut and click Yes to place it on the desktop.
Cheers!