I'm a sysadmin from the old school, and can't be scared away that easily. So after some digging into this problem I found that their buggy driver is the culprit. In short, it looks like it doesn't clean up after itself when unloaded, and when it's loaded by the kernel the next time, something is getting severely corrupted and plugging in a card again will freeze the whole system. Also this card doesn't have flash memory, so every time you plug it in, someone needs to load firmware into this beast to make it work. This "someone" is a daemon that comes with the driver package and resides in /Library -> StartupItems -> M-Audio Firmware Loader -> M-Audio Firmware Loader. If you run ps axw in a Terminal, you should see this process after driver installation.
As soon as the firmware is loaded, this card acts like totally normal USB card, complying with standard audio USB protocol. And Mac OS X (10.3.3 at least) has a generic driver for such devices! We have an alternative now -- just need to remove M-Audio's clumsy drivers from system, but keep the loader in place. When I did this, the card was recognized by system's own driver and has worked flawlessly since. The only thing which is missing after that is the latency tune up option; otherwise, Audio MIDI Setup.app from Utilities does everything that the M-Audio preference panel does. Here is procedure:
- If you have drivers already installed, remove them. If not, go to the next step. Use the OS X Package Manger tool to delete the "M-Audio Transit USB" package. After that, you still should have the FirmwareLoader.pkg installed (check in the Package Manager). Then just reboot and you're all set.
- Open the .dmg with M-Audio's drivers on it. You should see M-Audio's package, control-click on it and choose "Show Package Contents." Now you are inside of the package, go to the Packages folder and double-click on FirmwareLoader.pkg only -- don't touch other one! This way you'll install the loader only. Reboot. This is it.

