Ok, this problem is solveable too. When on console and you get bombed with squid-errors, you can open a shell via pressing 8 (maybe try several times till it works: Was so with my box.)
then change to /usr/local/sbin and rename squid to squidx or whatever. After a reboot no more squid-errors, because its not there.
I think its because of the reinstall of the packages: The binaries are not deleted, the config-files are still not available due to whatever, and you get bombed.
Install all as wanted and you will be on again. Don't forget to rename or delete squid again afterwards.