Not sure about the Babyface but my experience with USB midi is nothing short of a joke. But, I'm spoiled from the days when MIDI used "midi connections" and we never talked about latency.

Firewire midi seems to be much better but just recently I've upgraded to an RME HSDP PCIe card to try and get one step closer to the old days. Its just about there.

Your PC might need to be optimized if its freezing.

PS

I'm using a MOTU MIDI TimePiece for a router that goes to the FF800 or PCIe card. Its stable.

This problem only developed when I upgraded from the Delta 44 to the RME Babyface. Never had any problems before.
My gut feeling is that it's maybe a software design problem with Nuendo and that an upgrade to 5.0 might help.
Maybe an upgrade to Windows 7 might help. I don't know.

Win7 is definitely a step in the right direction but it would be better IMO if you had it all sorted before you upgraded. XP is solid.

The Dela doesn't have midi correct? What were you using before this for Midi?

The Delta 44 is an audio interface (no midi). Everything worked fine with that. I upgraded because the audio encoders on the Babyface are supposed to be better.

I hooked up my Emu 1 X 1. Not using the Babyface for Midi at all now. It seems to be working fine so far. No crashing. Seems like the more stuff (Midi, clock, etc) they add to an interface, the more it crashes. I wish the Babyface was strictly an audio interface.

Anyone use Nuendo? Is 5.0 more stable than 3.0? That's the only reason I would upgrade to 5.0

nuendo 5 is the bomb. I'd love to have it. Rainer has it buts he's not been by in a while. Everything I've heard about it is positive.

Nuendo 3.0 is the bomb too, although I've had problems that may or may not be related to the version. Sometimes when working with like 80 tracks or more if I copy a range and then paste it, the program will crash. Not sure if 5.0 would address it.