I booted to the other slice and things only got worse, to the point that the web UI and console wouldn't even load.
So I pulled the CF out and did a fresh reimaging.
2.0-BETA4 (i386)
built on Wed Nov 3 16:54:58 EDT 2010
FreeBSD 8.1-RELEASE-p1
Platform nanobsd (2g)
I reloaded my config and installed squid. It appeared to install normally, and the Proxy server: General settings page was prefilled with the expected values. But when I changed some of those values and saved, I again got the white screen with the repeat messages of a read-only filesystem and errors on lines 69 and 70.
Still the values I entered were saved. On the Proxy server: Cache management page all the text boxes were blank, and the disk cache type was set to null. I entered the desired values for all these and saved. Again I got the error page, but the values stuck.
At this point squid appears to be functioning somewhat, although performance is low due to what appears to be excessive IO on the disk cache, which could be related, but I have no idea.
The ro errors are perplexing though. Additionally, I got the following alerts right after loading my config:
SSHD failed to start.
There were error(s) loading the rules: pfctl: DIOCADDRULE: Device busy The line in question reads [ DIOCADDRULE]:
The former I have not seen before. The latter I have.
If nobody else is having these issues then I guess that points to a problem with my config, but I don't think I'm doing anything too extraordinary there, and most of my config changes were made long before I started having problems, anyway.