Sony Ericson Xperia touch screen keeps freezing, have to dislodge the battery to turn it off.

Had someone else with the same problem, it's similar to a PC locking up when it is performing too many operations at once and the processor gets tired of waiting for ram to provide info. He deleted alot of old applications, contacts, and anything that is old or not needed. Then he took out the battery and reinserted it and it works fine. Not sure if it will work for your Sony, but it's worth a try. If that doesn't work you may have to do a reset on the phone. Good luck!