Portable drive locks up on mac

LRussoPhoto

I have a buffalo ministation 3.0 that i use on my mac and pc. Over the past month or 2 it has started to lock up after sitting idle for a period of time. It has progressively gotten worse and now also freeze's shortly after I plug back in. Drive works fine on my pc, no issue's at all. I contacted buffalo and that said the drive is fine if it works on my pc and said the problem should either be with a port on the mac or a mass storage driver. Can anyone help me figure this out?