What is you problem.?

The subject says:

Not able to import my pictures from my Iphone to my mac

but the body of yur post says

Able to transfer pictures from iphone to computer.

What happens when you open Image Capture? Does the phone show up under devices?

Also see:

iOS: Disabling digital camera notification in Mac OS X - Apple Support

You can only import photos from the Camera Roll. If you are trying to import photos from Albums, it will not work.

No error message?

If no message note the time of the next freeze. After rebooting open the Console app in Finder>Applications>Utilities and look for log entries at the time of the freeze. Post suspicious ones here.