DiscoBiscuit, We're not ignoring you. Just been out of ideas.
The fact your not getting _any_ error boggles me. Is that from game console?
Tried from server control panel... does your host have some way to show responses?
Tried HLSW or other console watcher? Even vader posting in another thread here gets "unknown command: ulx"
We've seen v3.4 user/groups and ban.txt issues with users with various escaped sequences "\\" causing problems.
Though we wrote ulx 3.4 to be pretty rigorous regarding characters in names (to prevent exploits), it's possible the 'time' issue isn't time, but only when someone with a nickname joins that ULib ucl can't handle and faults out.
That's only one theory. Other than a few reported bug reports, which actually lock/crash the server, I've seen no "ULib/ULX stop working but server keeps running" due to that theory.
As for if an addon may be causing it...well, the troubleshooting for that really bites..especially in your case where 'time' seems to be the random case. Remove all addons... add one or two back at a time.
You may refer to the somewhat smaller list of addons to start with in another thread here on the forums regarding !menu breaking after seemingly random time.
It wouldn't suprise me if the resolution, whatever it may be, affects both your total ulx crash and that !menu crash issue.