[USR-TC] Having trouble with Macintosh modems

Has anyone seen any problems related to Mac's? I am having a real problem with Mac's connecting. I recently upgraded from 4 port cards to HiperDSP-24's. Thats when the problem started. I read of a old problem in the archives related to this, old TC rack rev's worked fine and when upgrading to newer rev's, Mac's had trouble connecting. It was a known problem with the rack software. Did it ever get resolved? My mac users have to dial in 3 or 4 times before they will stay on. This is driving me nuts! My software revs are: HioerDSP: 3.5.109 HiperARC: 5.3.3 NMC: 7.1.0 Any help is greatly appreciated. Regards Doug P