César,

>In the other way maybe you know how it is possible to close TXT files if 
>they are open.

Unless you know what application has the file open, and that application 
has an Active-X feature that allows you to control a running instance of 
it, the only way to do this, is to kill the process that has that file open.

The first problem is to determine which application has the file open, and 
the second problem is to kill the associated process. I'm not sure if either 
of this is possible or easy to do, especially if the file is opened on a 
different computer, but I do think that it isn't a very good idea to allow 
an application to randomly kill another application.

So, the approach that I would take, is to inform the user that the file is 
unavailable because it has been opened by a different process, and ask the 
user to (find and) close that process or file.

Hope that helps,

Andreas

Andreas Gehrs-Pahl
Absolute Software, LLC

phone: (989) 723-9927
email: Andreas.GP@Charter.net
web:   http://www.Aerospace-History.net