Maybe your save game got Corrupted. or MAybe the CD key in your save game does not match with that of the game. (just a guess).
try Hex Editing. (select a server) to put the CD key in again. read below for "how to"
from=>NFSPLANET=> "There are some problems with the savegames of Need for Speed Carbon. Actually every savegame contains the CD-Key of the game which created the file, which is quite a security risk and also a reason why we haven't put any savegames online yet.
If you want to know more: If you open a savegame with a hex-editor you can find a 20 characters between the hex-offset 0000003c and 00000050 which is the CD key.
To use foreign savegames you either have to replace this code, or update the cd key of your NFS Carbon to match with the one in the savegame file.. Both not a good solution, but maybe EA will fill this security hole with a patch."
Please make sure you never send out your very own NFS Carbon Savegame to anyone as the file contains your private CDKey, which maybe abused by others!
Hex Tutorial=> by nfsunlimited.net member "blah2"
"Any savegame with any cd-key can be hexed. Let's say you downloaded a 100% career savegame, you copy it to My Documents/NFS Carbon, start the game and bang, you get an error message. This can be solved pretty easy.
Method 1
Download "Hex Editor" (search it on google) and open the savegame which you downloaded. On the right you will see a pannel just like this:
(this image below is using a pirated cd-key and a new profile, just for example)
*img207.imageshack.us/img207/2764/hexpw9.th.jpg
You will see some similar writing on the downloaded savegame. Count from right to left 20 characters. That's the cd-key. Write it down or copy it somewhere. Then go to ...\Need for Speed Carbon\Support\Need for Speed Carbon_code. Open it and enter the cd-key which you've just written down. Beware! Write your own original cd-key or keep it somewhere so you can go and change it back when you want to play on your profile. Now copy the folder with the savegame into My Documents\NFS Carbon and look if the folder is named like this: A<nick> and the savegame file A<nick>,
where <nick> is the nickname. Hope it was helpful.
Method 2
I haven't tested this yet, and it may not work. Follow method 1 until you have to write down the cd-key from the savegame. Now open your own savegame with Hex Editor and copy your cd-key (beware of 20 characters), then paste it over the downloaded savegame's cd-key (be sure you pasted it exactly over the 20 characters).
Save the file. Copy it to My Documents\NFS Carbon and play."
