My Cd Changer in my '03 CTS says "CD Mechanical Error". I believe there is a CD stuck in the changer. Will the CD player reset if I disconnected and then re-connected the battery? Is there any chance of this spitting out the CD and solving my problem? Thought I might as well as while I'm at work!

If you are a born tinkerer you might be able to get it apart and release the captured CD. The usual cause is a dislodged label from a home burned CD.

If you try to disassemble the unit you will break the security seal and void the warranty on the unit.
The CTS radios have tape seals on each seam that will get you access to the inside.
Cycling the power usually does little to cure this problem.
Take it to your dealer, if it's under warranty they can order an exchange unit which will come in overnight or they can send yours for repair.
If it's out of warranty they can send it for repair.
If they tell the company that repairs the units that your discs are stuck inside WHEN they order the replacement unit, the company usually will mail your discs directly to you.

Don't use home burned CDs with stick on labels, they can (and often do) come loose and get jammed up in the player.
I have seen regular CDs get stuck in there too though.
I think it's between 100 and 200 dollars to repair one if it's out of warranty.
Plus whatever your dealer charges for labor.