I am a new mamber to the forum. I need to send a drawing to one of our vendor and I dont want him to edit the drawing. I have searched the internet and found that by certain addon application (like Cadlock, DWGguard etc.) this is possible. I have downloaded the dwgguard.vlx file and tried to add the same in my machine using appload command, but failed. Cad gives message "error: ARXLOAD failed". I have Auocad Mechanical 2011 in my machine with XP OS.Can anyone help on the matter. I also want to ask that wheather there is any other way to achieve the wanted results.

Does your agreement/contract with the vendor include you providing original CAD files?  If not, don't send them.  Any time you transmit original CAD files to someone else you run the risk they can change something you are responsible for without your knowledge.  Unless you feel okay with this you will always be better off sending drawings in PDF or DWF format.  If Autodesk really wanted to support a CAD editing lock feature they would do so.  But they haven't, and that's enough for me to protect original work unless it's being shared with parties I trust.  My advice:  Don't rely on 3rd party vendors to protect your critical drawings.Dave.

Either by and use CADLock or don't bother sending DWG files.  Short of that, nothing you do can't be undone at the other end by a person who is determined.