A warm welcome to you and Kiwi! How old is your quaker, if you know? Quaker parrots have the distinction of being the only parrots to build nests of sticks, in the wild they live in large colonies and share enormous community nests. Both male and female quakers are hard wired to defend their property from predators. This transfers to quakers who share our homes, all quakers are predisposed to be territorial but often, especially in single bird homes the behavior seldom escalates enough to be a serious problem. Quakers feel the hormone rush and respond, hormones can turn a consistently mild tempered bird into a high octane can opener. If your sweetheart is outside his cage for long periods (if so, you have a fortunate bird) he has more than likely claimed your computer table and any nearby items as his own. In quakers, hormones are often related to the onset of overpreening and plucking. It's possible your bird is female and she's preparing to lay eggs. In any case, I suggest, extra uninterrupted sleep, lots of dark green leafy vegetables and plenty of distractions in the form of destructible toys. The good thing about high hormone levels is, it's only temporary and your little guy or girl will return to normal. I think I would keep Kiwi away from the area he is protecting as long as he's attacking. Sometimes changing up his personal space will distract from nesting behavior. It's very wise to have your bird checked over by an avian vet, blood panels would be great to rule out anything serious and also give you a base for future blood work.