Yes, I was referring to that registry key.
Up to a point, I can understand that it annoys you not be able to choose the location of installation for your software. But sometimes it is necessary that it installs in the default Program Files folder.
Now, I don't think that's the case of tweetdeck but maybe some of their bugs were solved by installing in this particular location and that's the reason it doesn't let you choose your favourite folder anymore. I don't know. It may be another bug or a suggestion for the next version.
I don't pretend to know their reasons but maybe their installation process has changed for good reason. I think your comment was unnecessarily harsh.
But the one way to solved this is by telling Windows that the defaul program files resided in your d: unit which, after all, is what you do at the moment.
That's up to you, obviously.