I think you are doing the USB connection in the wrong mode. There are three modes of USB connections:
- USB Drive
- Sync Media
- Charge Only
I guess you are connecting with the "Sync Media" mode and that is wrong. You must connect with the "USB Drive". Normally, your Blackberry would ask when you connect which mode you want.
Choose "USB Drive"
You will then see a new drive letter. Then go to the home folder and un-tick "Hidden".