RE Ban crash - make sure the bans.txt file on your server in <gmod>/data/ulib/bans.txt isn't corrupted with lots of slashes "//" in one name/entry, or that it isn't more than a few Kb in size (most grow to 64mb in size when corrupt)
3.4 has known bug when banning players with slashes in name.
Quick fix is to rename bans.txt ... this will remove all temporary bans and ban reasons for all bans, but your permanently banned players will still remain banned (again, just won't have reason or who did them)
Re: Spectate - Think I've seen that reported before. No recollection of what caused it other than I believe a conflict.
[UPDATE] - It's DarkRP. According to
v3.50 - *(00/00/00)*
* [FIX] Fixed "ulx unspectate" not working in DarkRP (Thanks Ayran).
Now, whether or not this is actually a DarkRP bug we worked around, or a ULX bug, I don't know.
Either way, DarkRP is the root.