Happened to me last night. I just relogged.
I've made some changes, see if it helps. Retest.Relogging didn't fix it, The last scenes with XLR8moop where after I went to bed so that was around 7 hours later.
I've made some changes, see if it helps. Retest.
This is the exact problem I was talking about in my thread: http://www.herocraftonline.com/main/threads/immune-to-damage-mobs.29007/
Seems like as soon as you enter combat you can no longer cause damage from weapons held in your hand. Skills seem to be working now, unless they require a target (i.e. Kick, etc.). Relogging fixed the problem for me and several others for a bit, but would again happen later on.