The eye of the cd player and/or the CD have fog on them caused by condensation of water in the air because of the cold. Mine used to do this all the time.
Best suggestion is turn your dash vents on high hot for a bit, it will warm up the cd unit sometimes, enough to get past this issue.
I worked in a stereo shop for many years and saw many people in shock that their new $600+ cd deck they just bought for Christmas worked for a bit then errored every day when the car sat for hours cold.
As always, this is just my two pennies.
Jim
