Dell AC power adapter type cannot be determined

The “Dell AC power adapter type cannot be determined” problem description

I have brand new inspiron 2500.

Battery fully charged, when I unplug the charger from the wall, but let the plug in the Inspiron for a while (let’s say a night), when I startup my computer, I get the message “The AC power adapter type cannot be determined. Your system will operate slower and the battery will not charge. Please connect a Dell 90W AC adapter or higher for best system operation” (needless to say that the power adapter IS a Dell 90W…).

Unplugging and replugging the adapter solves the problem.

The problem happens frequently at Dell inspiron 2500, latitude cpx, latitude c600, latitude c610, 75uyf and so on.