Operating a data processing system comprises defining a plurality of profiles, each profile comprising a list of one or more applications; receiving a defined user input requesting a switch from a first profile to a second profile; hibernating the (or each) application listed in the first profile; and recalling from hibernation the (or each) application listed in the second profile. Preferably, a graphical user interface is adjusted to reflect a change in status of each application that has been hibernated or recalled from hibernation.