Before my DP 2.x upgrade came in 199whatever, I did a few projects in AudioDesk on my Beige G3 with my 2408. Straining the old brainpan here to try and remember.
OK… you still running OS 8, right? What Mac?
If not, what OS? version of AudioDesk? version of the PCI drivers?
Is your 324 card installed and your 2408 on? Do they show up in Audio MIDI Setup? If not, AudioDesk will not work (I think—been a long time).
Shut down and remove / re-seat your PCI-324 (or 424) card. Do the same with any SCSI and ATA/EIDE ribbon connectors.
When was the last time you replaced the memory settings battery in the 2408. I'm pretty sure it takes the ubiquitous CR2032 like the MIDI interfaces and most medical devices. Since the mk2 and mk3 don't have batteries it's easy to forget that the first version does.
Batteries... How long since you replaced your PRAM battery? That can really mess with your Mac's PCI bus if run down. If everything else appears to be correct, this could be the problem especially with a B&W G3.
Most PPC and earlier Macs take this one—but not all (not remembering that my 6200 did). Laptops do not.
http://www.amazon.com/SAFT-Lithium-Batt ... B000GED9NA