In the "Bootup and Shutdown" module, Squid will show as "Yes" in the "Running now?" column after a cold start. This is correct.
However, if you stop Squid using the "Squid Proxy Server" module, then start it again, it still indicates "No" in the "Running now?" column of "Bootup and Shutdown" module. This is not correct.
Which operating system or Linux distribution and version are you running there?
Ubuntu 10.04
Ok, I see the cause of this .. Webmin is not using the init scripts to start or stop Squid.
The work-around till the next release is to click on the Module Config link in the Squid module, and set :
Command to start squid - /etc/init.d/squid start
Command to stop squid - /etc/init.d/squid stop
yep, that did the trick