iPhone can be charged with wall charger but not recognized in Windows, in several PCs

Helllo,

I have an iPhone 3GS. I've done a lot of repairing and changed the dock assembly... twice..! The iPhone can be charged with wall charger but it is not recognized in Windows, in several PCs.

I get the "USB Device Not recognized” and Code 43 Error ...

And yes, I've changed USB cable, changed Dock Assembly and tried in several PCs... and thoughts?