Hardware problem: Touch screen -Need help-

[FedeIM]

Hello guys,

I am having a huge problem with my iphone 2G, my touch screen functionality is not working, the phone works as normal (excepting it takes much more time to boot than normally).
The story is that this is the second time that it happens, previuosly it stoped working so I bought the LCD+Touch replacement and changed it my self, it worked for a month but yesterday I grabbed my iphone and it didn't responde to touch.
I have changed my firmware and the problem persists.
When this happened for the first time, before buying the replacement, I fixed it several times by hitting the iphone (nicely) against my hand a few times and it magically started reacting to touch.

Does anyone have an idea of what may be causing the problem?

Thank you very much in advance.

[cpjr]

Sounds like something's loose. Plus hittin it aint the best idea

1one, I know you've got something to say

[FedeIM]

I been thinking that it migth be something loose but I have disassembled and assembled my iphone a lot of times and it stills happens the same.
Does any one know wich cable should I pay attention (I mean the one responsable of the touch functionality) in that picture?
Any test that I can do to find out where is the prob?