If you’re using MSN as your ISP, add the following line to /boot/beos/etc/servers.ppp: (you’ll have to change its write permissions first. See Tweak modem initialization strings for details):

MSN_Login e ogin:s du assword: dw S

You can use winicpfg in Windows to find DNS numbers for MSN and put those in too. Depending on how you connect to MSN you may need to add „MSN/“ before your username.
Do not check static IP in DUN settings.