Grumpy.. A couple of other thoughts I had.
1) What size power supply are you using? I recently added a 9800PRO graphics card and didn't pay too much attention to the Molex chain I attached it too. (had 2 x SATA and IDE Optical already on the chain). My Sata Drives started throwing me curves (longer load times, longer copy.. I could still use the drives but the performance suffered BIG TIME). After much troubleshooting I finally cracked the case and followed the power cables.. I unhooked everything and then re-attached the power cables to evenly distribute the power consumption.. Voila.. My drives worked as advertised again.
Norton does give you the option of register via mail, but watch the loading process. About the 80-90% range during load the system tries to either dial or LAN it's way out to register before you are even prompted. My buddy called it "stealth registration".
I would check the power connections, it is so easy to just add the molex to the first chain you find rather than the one that has the least power consumption.