OK, now, I just had to ask, mostly because I was lying awake last night thinking about it. (NO Stewart. IT. Not YOU. LOL)
You did try a complete uninstall of i1, and a reinstall of the newest ver, right?
I know about the lying awake bit, Ted (also thinking about the problem, not you, though I'm sure you're absolutely adorable...) and yes, I did several uninstall/download latest version/reinstall cycles. All to no avail. But thanks for the suggestion.
Apple hosed DDC capability on PowerPC Macs in 10.5.6. Match has limited DDC support for some displays. That's probably why.
That probably explains it then. Thanks for finding that out, Andrew. But what now? I guess that even if it works on a particular system using 10.5.6 that it might be less than reliable, or is it a case of if it works now it always will? Not a happy situation if you rely on calibrated monitors. Maybe I have to hope that 10.6 arrives soon and can support the i1. And if it doesn't, then I guess I have to get a calibration system that is supported. Trying to be as positive as possible, at least I now don't have to do my reinstall system bit.