Errors for users copying my ubuntu 12.04 LibreOffice3 files from my website to their MS Word

[Don Parsons]

Most of the users of my web site set up with Ubuntu 12.04 will be 
Microsoft users. I want to find out more about the difficulties they 
will have copying the LibreOffice3 files that I will populate the 
website with.
     When I copy *.odt files to Windows7 desktop I see that they appear 
as Word icons.
     In Windows 7, if I open one of these there is the message:  "The 
file "xxxx" cannot be opened because there are problems with the 
contents." [press OK]
     The next message is "Word found unreadable content in "xxxx" . Do 
you want to recover the contents of the document? If you trust the 
source of this document , click Yes."

     Is there a way to avoid getting these warnings and so alarming the 
Windows users of my web site?
Thanks
Don Parsons