Mac and TP won't recognize each other!

[Beejis]

Everything was fine and dandy with the two at one time. I'd plug the USB to the back of my mac and the other end to my TP and exchange .cab by .cab and sometimes pics and yada yada yada then one day I try and plug them together again and they won't recognize each other correctly.

It use to show on my TP what to sync with after I plugged in it, activesync or disk drive. I always selected disk drive then it would show up on the mac and I would do my thing. Now all it does is show that it is charging, nothing else.

Does anyone know of a fix so they will be in love once again?