I guess I learned a lesson tonight. I should have learned it earlier.
I have a D-Link DI-624 wireless router. Last week I upgraded to WPA (should have done this much earlier). Twice since then, I've lost access to file shares through the router. A reset of the router gets everything back to working.
I checked the firmware level against the latest firmware on D-Link's site and I was a couple of revisions back. So I downloaded the .bin file and loaded it using the router's administrative page.
When it finished, it wouldn't reload the admin page like it usually does. It took a few seconds but I realized that the router had reset to its default IP range. That wasn't all that it had reset.
It was completely back at the factory defaults!
Gone was my unique IP range. Gone was my SSID. Gone was my WPA key. Gone was my port forwarding. Gone was my ntp server. Gone was my log e-mail settings. Gone was my ...
Well, you get the picture.
30 minutes later, it was pretty well back where it was. There was one difference though. I had backed up the settings to my hard drive.