[DougShrapnel]

Reinstalling TCP/IP normally only fixes failure to connect at all as well as winsock.
The cable modem lights stay solid during disconnects? So we know it something in the Laptop. When something goofy like this happens to me. Sometimes it can be a resource conflict. I normally rip out the PCI Bus. This will remove all of your drivers so have em ready to reinstall. PCI Bus is a System Device in Device manager.
Windows should reinstall most of em on it's own. But can get pretty hairy if you don't have all your drivers. And it may not help. But if it's a resource conflict it might fix it.