Iphone will not sync with my laptop

Hi
I have an Iphone 3g and macbook laptop. Recently my iphone has no longer been able to connect to my computer. This problem is specific to my laptop and specific to my phone in regards to the USB ports as they are in working order and when connected to another laptop it works. I have reset the PRAM recently thinking it was my USB ports and have also recently performed a hard reset on my iphone since the iphone 4 update slowed it down. When the laptop is shut the phone charges and when resetting the PRAM the phone connects for a few moments and then once the laptop has fully loaded stops working. Anyone offer any help as Im not sure if its a hardware or software problem with my phone or laptop. I have already been suggested to reinstall AMDS iv tried that and had no success.
thnku

Log-in in to your iTunes account on your new Mac and then sync as normal. You'll be asked if you want to copy stuff from your iPhone to Mac (which you probably want to do) and then you should be able to continue as normal. Remember to authorize your new Mac with your iTunes account as well.
Besides there is a step by step instruction on how to transfer or backup iPhone contents to Mac.
Hope it can do you a favor.