Sudden Loss Of Internet Connectivity?

Two days ago I lost internet connectivity suddenly on my desktop (Dell XPS 630i, onboard Nvidia network controller, running windows 7 Home Premium 64bit) and have been unable to restore it. As my laptop (winXP sp3) can still connect to the internet and the router settings have not been changed (Dlink DGL4500), I'm making the assuption that my networking problem resides on my desktop alone. the network adapter gives me a 'limited connectivity' symbol and refuses to connect to my network, even though the router acknowledges the desktop's wired connection. The troubleshooting diagnostic sometimes finds nothing, sometimes finds that the computer is not obtaining a proper IP, and sometimes claims the problem is the router. I've also disabled windows firewall. Throughout this whole process I have been getting a 'Drive Power State Failure' BSOD during restarts (about once every four or five restarts, not consistently).

At first I was unable to replace the drivers or uninstall the adapter through device manager. After reinstalling the drivers using the Nforce 650SLI drivers on their website, I was able to do this, but this did not solve the problem. I also did a windows restore to before the problem occured, also with no luck. I've been through the event log and there are numerous code 5007 errors, which just tell me that the adapter timed out during an operation. I've also read through some forums online and tried several solutions including adding a DhcpConnBcastFlagToggle line into the registry: SOLVED: Network Icon Exclamation: No Internet