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Do you have a protective cover over the screen? These can sometimes interfere with the touch.
I suggest that you try to repair the phone software using PC Companion..
Before repairing your device you may want to backup your information first. Check out this topic for more information on how to.
How to backup?
If the issue should still remain I think that this needs to be examined and fixed at a repair center. For more information about how to submit your phone for repair and where, contact your local support team.
I would not consider this a general issue. Try to repair the phone software and get back to me with the results. If the repair doesn't help, you can send the phone in for repair as it seems like it's a hardware issue.
As I mentioned in my last post you can send the phone in to a service center for repair. Contact your local Xperia support for more information. See my signature for contact info.