Go to the startup folder and remove any icon that has to do with your monitor except for the one you want to use (ex. Spyder).
Then go to your display properties in the control panel. Click on the settings tab. Click advanced in the lower-right corner. Click the color management tab in the new box. Under the "Color profiles currently associated with this device:" you should see the calibration software you are using (ex. Spyder). If there is anything else there, remove it, and then hit "add". Find the "Spyder" profile and save it as your default.
Restart computer, and go back into display properties and color management tab to see if the profile is there.
I think it would be helpful if you could give us a little more info. I for one don't understand exactly what you mean by "auto adjust". The eye one software makes its calibration adjustment during start-up - are you referring to that? If not, what exactly is happening and exactly when during the start-up process?
What exact model of the Dell do you have?
I use XP, a Dell LCD (2407), and Eye-one and the only "auto-adjustment" I see on start-up is what eye-one does as I mentioned.
Dell LCD, Windows XP