W2000 Dialup problems

I have a W2000pro box with Motorola Bitsurfer Pro ISDN. After installing W2K SP1, I could connect to my ISP but could not access the web or e-mail. I uninstalled SP1, now everytime I disconnect from my ISP I must reboot my system before I can connect again. Any ideas to the failed SP1 install or the current problem?