This has been happening since I first joined the rr3 server. Whenever I exit the inventory of a block, say, a Redstone Furnace or a chest, or I close my character's inventory, my inventory pops right back up. I have to close it, sometimes several times before I can actually move and place blocks. This only happens on the rr3 server, it doesn't happen on the Bevo server, it doesn't happen on any of the Vanilla servers I play on, just this one.
