Many people have experienced this.
You most likely have a Mk3 and have likely burnt the CD in the wrong format.
Tip: Mk4 says "DVD" on the nav drive front panel, Mk3 does not.
Mk3 is sensitive to CD format, a Mode1 CD will crash the system.

You need to eject the CD, throw it away, and burn a new CD in the proper Mode2 format. I use ImgBurn, it has never let me down, and faithfully burns the same format that the image is in. Check the mode before you burn!

For a CD that will not eject from the navigation computer, follow the procedure below:
1. Remove the navigation computer.
2. Unplug the voltage supply (blue connector).
3. Reconnect the voltage supply and immediately press the eject button repeatedly until the CD in the drive is ejected.
4. Insert a new navigation software CD and restart the installation process.