There is a new Mac HDSPe driver available. Version 2.72 should bring these improvements:

- Changes in the kernel driver's memory management (might fix a mysterious freeze on some systems)
- Bugfix: ExpressCard MIDI driver hangs after standby
- ExpressCard: HDSPe Settings disappeared or crashed after standby

If you are affected please try if this driver solves the problems.

https://archiv.rme-audio.de/download/hdspe_x86_272.zip