iPhone 4S doesnt show charge symbol and charges very slowly on brand new MacBook Pro. Not recognised by iTunes. Charges fine on Asus laptop. iPod charges fine on Macbook Pro

Hi!

I'm trying to fix a problem I'm having with my iPhone 4S and MacBook Pro.

I did manage to connect it initially and set it up with XCode as well as iTunes.

Today I have spent two hours trying to connect it to my MacBook Pro and I have so far found the following...

iPod 2G - charges from MacBook Pro, Wall Charger, Asus Laptop (works with both my Apple USB cables)

iPhone 4S - doesnt charge from MacBook Pro, but does from Wall Charger and Asus Laptop

                  - Asus Laptop running Linux Mint recognises the iPhone as a device with 'lsusb' and you can browse photos etc

                  - MacBook Pro doesn't recognise the iPhone as a device with the 'systemprofiler' equivalent of lsusb

                  - Interestingly, despite the charging icon not showing, the iPhone either maintains charge or very, very slowly charges

                     when connected to the MacBook Pro.

Any ideas as to what might be wrong? I've tried both the USB ports on the MacBook Pro and no difference. I've tried the 6 ports

on my old Asus laptop and they all work fine!

Thanks for your help!