by wave 6 couldnt see my shots, by wave 12 the monsters were invisible... but they could still kill me.

1st time I had this problem on the server I assume it's the map, but I dunno.

Thought I'd mention it just in case it happens regularly to others on this map, just in case it's the map and not the server or me.

Edit: Did a reconnect and that seem to fix it, but when a monster killed me my game crashed with the usual crash. Upon rejoining the server it informs me my name is not allowed and won't let me on, everyone else died in the meantime and it was the end of the map. bah not happy

It's a known issue, and happens on other servers too. As far as I know, isn't tied to particular maps. All you can do at this point is reconnect when that happens - restart UT if it persists.