AutoCAD 2010/2011/2012 DWG Format

[#1]

I'm working in AutoCAD 2010 and have just recently begun getting the following errors when opening any file.  Even files that I have created from scratch in the same version of CAD.

This is the error I get when I open the file:

"To be fully compatible with this version, save the drawing from the original application as AutoCAD 2000/2004/2007/2010 format with AEC objects exploded or with Proxy Graphics enabled"

Then, when I try to copy/paste from the menu bar (as opposed to just "c" from the keyboard or icon), I get this error:

"This application has detected a mixed version of AEC objects participating in this operation.  Newer AEC objects will be disallowed from participating in this operation"

It happens even when it's just lines - no objects at all.

What is going on, and how do I fix it?  Thanks!

[#2]

Did you recently experiment with R2013? If not, someone else did with all of these files and now all the AEC content has been upgraded and taken out of your 2010 version's control. Or you keep dragging content (or using a template file) saved down from R2013.

If you don't these AEC objects, -EXPORTTOAUTOCAD command (there is a dash in the command name) in 2013 can get rid of them for you. It may work in 2010, but I've not had good luck with it myself.

There is no other fix, unless you want to go ahead, pony-up, and upgrade to R2013 today.

[#3]

It started happening after I opened a file from a consultant, so yes, that's a possibility, but the other files are mine, created by me, and never opened or edited by anyone else.  That's what has me confused - it's doing it with every file - even ones that I haven't opened in months.

So, if I'm not ready to upgrade to 2013, I just keep hitting "accept" or "ok" and ignore the errors? 

[#4]

In my first reply, second paragraph, is a fix if that works for you and your consultants: talk to each other and decide what's best.

Existing files don't suddenly become laced with AEC content on their own: you or someone introduced them in the file(s) with a copy/paste or INSERT or XREF or more.