For what it is worth I never had the emu lock up on me (except for the games that don't work like Actraiser). I always play with sound on, and I am running FW 2.0. The only bug I have had is the sound loudness seems to shift back and forth between left and right speakers randomly.
Just found something on my gp2x...
This happens if the phase for one speaker is wrong (which it was in my case).
Might be the problem on more than one gp2x (if not on all...)