problem with touch while charging the phone

[Woshi]

Hello,

I bought my Sony Xperia L 2 months ago and for the first time when i put the phone charging in any wall socket the touch is going crazy. its so hard to unclock using the pattern because is like if I left the finger of the screen. To avoid this i am charging the phone in my laptop but it is not practical and profitable.I read something similar in this forum but what can i do?

[AnandSRM]

Sometimes my phone is getting discharged by itself while being plugged for charging.Is it possible that since the phone has charged to its full extent,it has discharged automatically..??? But somedays ago,it discharged when on 70% charge!!
I can't really understand what the problem..