Dial up access problem

I have several toshiba laptops Joined to my domain, which use outside ISP’s for dial up access. After applying the MSblaster Patch These laptops are unable to access the internet through dialup. I can successfully Ping IP Addresses over dial up connection but unable to browse pages. if unjoined from the domain, i can access isp successfully. All other brand laptops are running fine. Is there something with my win server 2000 policy settings that might be interferring somehow?