MISSING SAVED GAME FILE
Saved games (or other saved data) are easily accessible through the game when COD4:MW is installed. Once it has been deleted, if you have not deleted the saved information, you have to go to a specific directory.
If you are on XP, this is straightforward. You go to the folder where the game assets used to be stored (default is C:\Program Files\Activision\Call of Duty 4 - Modern Warfare) and look for the Players directory.
However, if you are running on Vista in a typical fashion (user mode with standard settings) you have to find the virtual store. This will depend on your username. You have to combine the path to the Virtual Store with the path from Program Files. In general terms this will be the following: [HDD]:\Users\\AppData\Local\VirtualStore\Program Files\Activision\Call of Duty 4 - Modern Warfare. In order to see the AppData folder, click on Start->Control Panel->Folder Options. Click on the view tab, then click Show hidden files and folders.
POTENTIAL SAVED GAMES PROBLEMS
When playing COD4:MW on a Windows(R)Vista system, there is the potential for Saved Games to "disappear" if you switch from Standard User level to Administrator level of security. This is because of how Vista deals with saving files into the Program Files directory. If a user saves games, which are typically stored under the Program Files directory (by default in C:\Program Files\Activision\Call of Duty 4 - Modern Warfare\Players), they are not actually saved in that folder but in a Virtual Store. Windows(R) does this to protect the security of the Program Files folder, but allow legacy titles to continue to function on Windows(R)Vista.
However, when a person elevates to Administrative mode, the link to the Virtual Store will be broken and only files in the actual Saved Game directory (under Program Files) will be visible. Switching back to Standard User mode will restore the link. Interestingly, in user mode, both the files actually in the Saved Games folder and in the Virtual Store will all be visible, although you will not be able to delete any files in the actual Saved Games folder.
This issue will not occur unless the game is installed in a privileged area (e.g. C:\Windows or C:\Program Files), although this is the default. Also, this won't happen if the User Account Control (UAC) is turned off.