/thrash/
vi. To move wildly or violently, without accomplishing anything useful. Paging or swapping systems that are overloaded waste most of their time moving data into and out of core (rather than performing useful computation) and are therefore said to thrash. Someone who keeps changing his mind (esp. about what to work on next) is said to be thrashing. A person frantically trying to execute too many tasks at once (and not spending enough time on any single task) may also be described as thrashing.
Compare multitask.