When saving over an existing save, the game first saves to a temporary folder (ie the same name, but with a .tmp extension), in case there is a problem during the save process, then overwrites the old save and deletes the temporary folder. There will be an extra 20MB or 40MB (depending on whether you have been to the BF yet for that act) of hard drive space used during this process, but that should be freed up when it is done.
If the free disk space is not being updated correctly, then ScanDisk should help. Unless there are temporary folders piling up with each save and not being deleted, that is a distinct possibility.
As long as you do not have background programs running that write to disk and cause ScanDisk to keep restarting, and do not do a thorough scan, it should not take very long. If that fixes the problem, it may not reoccur (or at least you would only need to rerun ScanDisk every 50 saves, or whatever, depending on how much free space you actually have).
Deleting the files in the dynamic folders should not cause the game to crash (they are empty when the game is first installed, after all).
If you reset the configuration as prompted when you try to start the game the first time after a crash (or power failure, etc where the game is not shut down properly), I believe the files in the dynamic folders do get deleted.
A corrupt file is actually fairly rare, but it is easy to check and clearing the dynamic folders shouldn't cause any problems, so that is one of the things to try when a problem does not have any specific known causes.
[color:"orange"]Is there really no other way as to use third party programs to look for missing harddrive space?[/color]
I'd run ScanDisk first, to see if the space is actually missing, or not. An
uninstall program or
file monitor (more technical) may help track down what is happening if you really are using up drive space each save.
[color:"orange"]I can't believe that me and the other person who made the original posting are the only ones with that problem.[/color]
Perhaps not, but it is not very common, and I don't recall anyone else posting about it.