Make sure you use the latest version of Real.
The program might be looking for media to play from that HDD. At the same time, Windows is trying to open the same drive and to give you the whole Autoplay options menu. These can cause a temporary freeze.
If the freeze lasts the whole time the drive is connected, regardless of the duration, then I would recommend a disk clean-up and a checkdisk on that drive with the /f/r parameters enabled, then a defrag. That should ensure the HDD is OK.