Default hardware problem (!?)

I've replaced my broken touchscreen with new one and everything works fine until I try to call someone. i choose person from phonebook and then screen freezes but I can hear dialtone and person on the other side. I can't even disconnect a call. Then I must take out battery and put it back.
Same thing happens when I try to call someone with viber!

I flashed a new rom but same thing happens! What can I do!?