>No. If you have overwrite 'true' then the fact that the destination already exists should not be a factor. See the code Gregory posted - an exception can be thrown if permissions fail.

I have overwrite there but the directory is always empty when I start my copy. So, the overwrite flag is not a factor here. The initial transaction is the copy. While it is in progress, the other program succeeds to take a hook to start copying that file somewhere else but the copy I am doing is not finished yet. This is what I am wondering if the CopyFile() is really locking the file or while the copy is in progress, anyone can get a hold of it.

IAC, I have adjusted to copy the file as lcFile+".TMP" and then I rename it to lcFile.

>What's the errorCode in WinIOError() ?

I do not have it.