Player formats itself switching between pc/mac

I vaguely remember seeing someone post something similar, but I could not find the thread.

So the M6 player is running v2.004.4, I've yet to test it with 2.004.5 but I can only assume the same problem happens.

I'll have to get the exact steps together so as I can reproduce it 100% of the time, but I just wanted to get an idea whether anyone else has had a similar experience. Generally the player gets plugged into a mac (OSX 10.3.9) and music is copied to it. Everything is ok. Then, it gets plugged into a PC. Everything is ok at this point as well. As soon as it gets plugged back into a the mac, it becomes unresponsive and doesn't show up on desktop as mounted. So the only way to remove it is to unplug it. It stays like this until it is plugged back into the pc where it is formated.

I've only experienced this once with my player since I rarely go between mac and pc. But a friend of mine does, so I'm trying to figure it out for him. Those are just general steps above, I'm going to sit down and get the exact steps and where it seems to format itself tomorrow.

Has anyone else run into issues swapping between mac/pc?