Problems with 20" iMac monitor Profiling

Hi

I have a 20" iMac (glossy screen) running OSX 10.5.8 and am calibrating the monitor with a brand new Eyeone Display 2.

The problem I am having is that the monitor profiles are quite different from one to the next. If I calibrate the iMac in the morning then again at the same time the following day, there is a difference between the two profiles. If I apply each profile via the OS Screen preferences I can see the difference. I would expect to see a difference say over a 3-6 month period but not one day to the next.

I have trolled through these forums and others looking for people with similar issues but haven’t found any yet. I have also read through the Colorwiki pages to check the different options and settings etc.

The settings I am using within Eyeone Match are: white point 6500K, gamma 1.8 and luminance of 120. All pretty standard. I don’t use the ambient light check. I then just follow the instructions.

What am I doing wrong or what settings have I missed?

Thanks.