Help with LogicPro7 and 2408mk3 issue...

[skydotcom]

I••™m getting what appears to be clock-related digital noise ---a rash of clicks--- on some of Logic••™s instrument plug-ins in any projects with a sampling rate higher than 48 KHz. The sound is worst with Sculpture and EXS24 (or any of the Garage Band instruments based on them.)

My system ---at least as it concerns this issue--- is very sparse and consists of:
Apple LogicPro7.1.1 on an
Apple PowerMac Dual 2.5MHz w/ 2GB RAM running OS 10.4.3 with a
MOTU PCI-424/2408mk3 audio interface

The problem is occurring at the 88.2 and 96 KHz sample rates. (Interestingly, the effect is similar ---but more extreme--- at 176.4 and 192 KHz, rates that the 2408mk3 doesn••™t support.)

The problem disappears when I use built-in audio instead of the PCI-424/2408mk3.

Any ideas?

Thanks!