100% sure touchscreen problem is hardware just look at this

[Lxrg]

http://youtu.be/FJW_gBAmtIQ

[_alexdon_]

So you cannot unlock your phone?

[Lxrg]

Not with a case on it or in a table or in bed or over a magazine or what ever
only holding it with my hands 90% of the time .
Allready in warranty.

[_alexdon_]

Well,it is a known problem with Xperia SP also,on flat surface the phone does not respond to touch.

[Lxrg]

Happens in my hands with a case also. Not only in flat surface and as u can see in the video. If i touch metal frame it it doesnt have any problems

[Lxrg]

Most of the time.......

[_alexdon_]

This could be hardware problem,maybe a certain lot of phones has that problem.But it looks like software also,it is bad optimisation I guess.

[Lxrg]

Mine is c6096 everything perfect only that terrible issue white one had first firmware installed, pretty sure is static or grounding issue result of glass and aluminum combo

[_alexdon_]

Have you updated to 4.3?Maybe it will fix it.

[Lxrg]

Updated, to 257 still there. Flashed 4.3 same restored same re instaled 257 same