Have you tried either of the last two suggestions in the installer FAQ? Both are possibilities from what you've described.
[quote]Is there another method or file package I can use? The install file currently used for ver 05 has not thus far been resolved.
Just to reiterate, all other installs work fine on my system, including earlier versions of DO Pro. ?????[/quote]
My guess is the installer you downloaded is corrupted. Sometimes web browsers stop downloading before the file is complete and don't tell you. The last suggestion in the FAQ tells you have to check if that happened.
Nothing happened to your File Type Groups associations. We just used them to override what's in the registry.
If you want, run FileTypeDiag on the extension you were double-clicking and post the results in a zip/attachment. I'll see if that reveals anything.