Sudden issue with 003 and low latency

[Linusoli]

Problems with 003 and Low Latency Monitoring
Hi I'm having a major problem with Pro Tools today and would be grateful for any help.. I've been running pro Tools 10 LE on my laptop for years with no ill effect. I use a MacBook Pro with OS 10.7.5. Looking to boost my processing power , I recently bought a 2006 Mac Pro and then replaced the processors, RAM, etc. It has OS 10.6.8 which i believe is the highest it can go. I installed Pro Tools 10 from the disc onto the Mac Pro and am suddenly dealing with a major issue. Turning on low latency monitoring causes the signal to completely disappear. The Avid 003 drivers are completely overriding everything - where, on my laptop, I had control in the "hardware" window to pick the clock source etc, now everything is just defaulted to the Avid Driver. As a result, low latency monitoring is effectively disabled. This is causing a pretty insurmountable workflow obstruction. I've been messing around for hours but simply cannot find a way to achieve the same settings on the Mac Pro as on the laptop. Sorry if I sound frazzled, it's only because I really am... Does anyone have any knowledge or insight into this issue?