I need help with two files that do not open files. When you open the autocad gives an errorfile is not valid. Anyone can help me?The files are in the following link: http://wtrns.fr/RMlHL7XgNw-rAAthank you

First check Tip 5102-Drawing file is not valid (error).  It is listed as a related CAD tip under your post.Note: You can download, for free, AutoDesk DWG Trueview to open drawings and save them to an earlier file format.