I had something similar. For some reason, while upgrading to 2.02NA, I "broke" something in my configuration and had to re-install and re-configure. I manually configured the WAN, but it didn't connect. I had to reboot a couple of times and it started working.
I wondered about the MAC address, but I didn't touch it. Never set it to "my PC". I just checked, and my MAC addresses (WAN and LAN) are *not* the same as the PC I used to configure the connection.
At this time, everything is working fine. Just got the DIR-825 yesterday; will be interested to see how long it goes between re-boots...