"without me taking any other action other than logging in" I assume that means the mini may be running 24/7 and that you don't usually do anything on/with it? If not, disregard all the following. If so, what does ChronoSync, BlockBlock and Dyn Updater do? Not sure why you'd need Mail running, and Spamsieve would probably not run without Mail starting up.
My mac mini runs as a household server and is awake 24/7, and no I typically don't do anything with it requiring login or manual interaction unless something needs to be updated, restarted, etc. I typically restart the server every 7-14 days just for good housekeeping purposes. It serves 3 key functions:
-Weather station management via WeatherCat including template and data uploads to Weather Underground, PWS, and my personal site on a 3rd party hosting service.
-Spam filtering of my email accounts on a real time basis via SpamSieve and Apple Mail running 24/7. This process filters spam out of my IMAP mail account inboxes before it ever reaches my laptop, iPad or iPhone.
-Backup & photo/music sync services for the 3 other Macs in our household via Carbon Copy Cloner, Chronosync and Backblaze (for cloud backup).
As for Dyn Updater, my ISP (Comcast) uses dynamic external IP addresses that are subject to change so I use the DynDNS service to work around that and be able to remotely reach the mac mini and other services in my home reliably. Dyn Updater is DynDNS' background app that locally monitors my Comcast dynamic IP and advises/updates DynDNS when my home Comcast IP address changes (often if the modem reboots itself).
BlockBlock is a small background app that prevents installation of launch agents and daemons, etc. without approval. It's a tool to monitor/block malware components since the mini is exposed to the web 24/7.
All of these apps and services have been happily coexisting for well over a year with no problems and may have nothing to do with the WeatherCat hangs I been experiencing recently. But I'm grabbing at straws and trying to figure out what to try next. All thoughts and suggestions are more than welcome!