OK, I tried disabling ipv6 in firefox. Well, I couldn't ping anything, so I'm not sure that's the problem. syslog is just way too long for it to be useful, and I'm sure the error is so buried to make it impossible to find now. I will check it immediately the next time this occurs.
I'm going to upgrade my system to 13.1 and the latest kernel. Hopefully that will fix the problem. If not, I'll be back.
It's tricky because it does not happen often. I just thought I might have missed a step somewhere in attempting to restart my internet connection. dhcpcd, modprobe and inet1,2,d are the only things I know of. A while ago I had a problem and searching the internet I found a file in /etc/udev/rules.d that I edited to have the correct mac address and that fixed the issue. I just thought maybe someone knew a "secret" like that.