I had the exact same problem. And it took me a while to figure all this out but I got there in the end. The info on the Activision website isn't very helpful. But I just noticed one day that my game wasn't saving.. right at level 24.. odd.. So here is my fix. Oh I also sent this to Activision and I signed up to this forum just so I could post this. This is on Vista Ultimate also... UAC is on.
Step 1: Go to the following directory:
C:\Users\YOURNAME\AppData\Local\VirtualStore\Program Files\Activision\Call of Duty 4 - Modern Warfare\players\profiles
Step 2: From the top left choose organize and then Folder and search options. Select the view tab and tick show hidden files and folders. Click OK and return to the above directory.
Step 3: Copy the now visible profile and paste into C:\Program Files\Activision\Call of Duty 4 - Modern Warfare\players\profiles. Also paste a copy to your desktop as a back up and delete the file that is in the Virtual directory. Make sure it is empty!
Step 4: Right click on the folder and if it shows the Hidden option is ticked... uncheck it. Click ok and open the folder. Now highlight the files inside. Should be 3 of them. Right click and go to properties. If they are showing up as hidden, untick that also.
Step 5: Now to test. Open COD4 and it should automatically load your profile. Choose Create Class and rename any class to a different name. Quit COD4 and open it up again. Check to see if your class was renamed. If it was, you are in luck and back in the game!
Step 6: Refer to step 2 and choose to hide your system files again.
Step 7: Make sure you make regular backups of your profile. You might also want to choose to right click the COD4 file and choose the option to always run it as an administrator.
Hope this is of some benefit.
Worked the trick for me!!
Edited by krucigen, 21 January 2008 - 04:26 AM.