I registered just to let you know that you're not alone...
However, by chance, I had a "non-responding" adobe X window open while I was doing the work of registering and by the time I was done the document had actually opened. I opened it a second and third time and noted that it took roughly two minutes to open.
Clearly, that is horrid program responsiveness and should be addressed but in the event you MUST get to your document... give it a few minutes to open.
I also registered just for this comment, since there doesn't seem to be any other acknowledgement out there of this bug.
Zombie's right. It will open the secured doc after two to three minutes, which is more than unacceptable. The problem is Protected Mode. Go to Edit | Preferences | General and uncheck the Enable Protected Mode at startup box.