I am experiencing similar issues. A couple weeks ago, I upgraded from 7.0 to 7.1 with no problems. This afternoon, one of my users reported that the webmail was down ("Firefox cannot establish a connection to the server"). When I tried accessing Server Manager, I got the same response. However, the admin account works fine when I login on the console. Also, the IMAP mail service is working okay (all of these are local accesses from my company's internal network).
I decided to reboot the server. That was a mistake. Now, not only is the web service down (both Server Manager and webmail), but the e-mail service is down, too. When I launch Mozilla Thunderbird, it tells me "Unable to connect to your IMAP server". I can ping the server, so I know that it's up and running.
The server was configured in server-only mode, and there is no firewall between my PC and it. This doesn't appear to be a firewall or network connectivity issue. Something changed on the server over the weekend, and I have no clue what that was. Any idea where I can start looking for the culprit(s) of these problems?