Ok, I was having that same problem. So after the 3rd time, I called EA Tech Support.
This is what you have to do:
First: Delete the BF:V Directory (all of it)
Second: Delete all the Registry Settings.
To delete the registry settings (there are 3 of them) you have to go into your Windows Folder, open the RegEdit thingy.
Then open HKEY_LOCAL_MACHINE, then open SOFTWARE, look for EA GAMES, open that and Delete all the Folders for Battlefield Vietnam. Now close EA GAMES, and open ELECTRONIC ARTS, again Delete the folder that says Battlefield Vietnam. NOW the 3rd Location is the one I couldn't find. Close the Electronic Arts folder, and scroll down to and open MICROSOFT. Look for the folder called WINDOWS, then open the folder that is called UNISTALL. Now you need to look for a folder that starts with {E35B3..... and Delete this Folder.
Ok, Now everything that has to do with BF:V is gone from your computer.
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