I am having problems controlling which version of AutoCAD my drawings open in. On my machine I have AutoCAD 2004, AutoCAD Electrical 2007, AutoCAD Electrical 2008, and AutoCAD 2010 installed. Everything was fine until last week when I installed 2010.After I installed 2010 it became the default application for all ".dwg" files. Typically I double-click a file from within Windows Explorer to open them. I need them to open in 2008 and am not having luck re-associating the files with this version. I have tried going to the "Tools...Folder Options...File Types" menu and selecting the "acad.exe" executable for 2008 as the application for all ".dwg" files, with no luck.Now when I double-click a drawing file it opens within 2004. I believe part of the issue is the fact that the executable for all version of AutoCAD is "acad.exe".  I understand Autodesk prefers drawings be opened via the "Open" command from within the software, however for my application this simply is not an option.Is anyone aware of any variables or other methods which may control which version of AutoCAD is associated with the ".dwg" file type?

I would blow away the 04' acad and 07electrical. There old, and theres no reason (that im aware of) to keep them. Should solve your problem. And if you have to save down to anything, you can do it automatically.

acad.exe worked fine with multiple cad programs on my desktop.
 
That was before I used a registry cleaner. Ouch! That hurt.
 
Reloaded. Used the registry cleaner. Too many times.
 
Steer clear, I hope you're not using one, a registry cleaner!
Buyer beware!