[Is there anything you can do about a particular person who keeps harassing you?]

Weapons are not the answer. If they keep coming back for more, don't give them a reason to wind you up more. Besides, most SL weapons are made for Linden Damage Combat and meter based combat systems like VICE or CCS and some weapons even crash sims, so it's best you do not resort to using violance. 

It is better just to ignore them via blocking them every time they try to harass you. Continue to do this until the harasser has become completely board of trying.

[how do I unequip graphic crashers]

Someone recently gave me a GPU crasher and renamed it. I can't unequip it after the 20 seconds before it constantly kills my viewer. 

I need help!