There is an Item in my inventory that stays in it's place and will not move no matter what. I am on a server so there is very little I can do about it. I am in creative mode. If I try to use the hotbar slot that it is in, I can't break blocks or interact with anything... can someone help me!?!?
Is this a craftbukkit server with plugins? Sometimes, servers will pin a certain item to an inventory slot, so that those items can be used for special purposes. Since you mentioned that you are on a server, this is the only thing that I can think of.
If you haven't already, you can also try dying, as well as re-logging.