DWG file not autodesk

[Spyder109]

I am using Building Design Suite 2012 and trying to open a file that was emailed to me, when I try to open it I get an error that says "This DWG file was saved by an application that was not developed or licensed by Autodesk. What do you want to do?" When I choose continue opening DWG file it will open the file but it seems as if things are everywhere and outside the limits of the title sheet. I would think that possibly this was the intent of the drawing and they control the items outside of the title block with clipping or layer control, but here is where the weird part comes in, when I saved the file to my computer and try opening it from there (as opposed to directly from the email) when I click on it and it gives me the preview before opening the preview looks correct like the drawing is supposed to be. I have tried opening the file in Architecture 2012 and in TrueView 2012 and get the same results. Has anyone seen this before or knows a way to fix this? Thanks

[JD Mather]

..., but here is where the weird part comes in, ... it gives me the preview before opening the preview looks correct ...

Not weird.
At some point the software created a screen capture thumbnail bitmap preview image of what was on the screen. This is not necessarily indicative of what is actually in the file.
A lot of people have been confused by this preview image when they have a corrupted file, "...but I can see it in the preview...". Not saying your file is corrupted as I am not familiar with the programs you are using.

[daft vader]

I have had this happen to me in the past but with text within the file being to large, I think I just resized/scaled to correct the problem, its as if the scales are somehow different or read wrong when added to autocad