I'm not sure why this got moved to the After Effects forum. It's affecting multiple applications....
It's in the right place, as apparently the "video people" would have the most to say about it. Anyway, I think at this point it's anyone's conclusion that for now this release is a complete bust and until the first patch update comes along you should stick with CC 2014.
I'm also on OS X 10.10.3 and am having none of those issues. This makes me wonder about your system resources and what other software you have installed or running.
One of my animators installed the updates on his new machine ( same MacPro 2013 config), and I don't doubt there is something somewhere on my setup that is causing and issue. But, since I'm getting erroneous errors that aren't leading to a solve, I'm not sure what the next steps are. I definitely have Quicktime. I have the latest system software. I've disabled anti-virus and a network monitor (both of which have never presented a problem with previous CC installs).
I'm pretty good at troubleshooting this stuff, but at a bit of a loss right now. If I was having issues installing, I've had to reinstall CC Desktop in the past, and deal with app cleanup, etc. But this is post install. Not sure where the conflict is.
Most of the third party apps I have running in the background are all related to file share (box, dropbox and media-fire desktop). Nothing that augments the system other than the two "scanners" I disabled.
I restarted my machine and only ran the CC installer for AE and Media Encoder. Launched AE and it behaves exactly the same. After it's done launching it hangs, and eventually the interface loads up. But it shouldn't take a minute to get to this point and there are clearly some issues if I'm getting errors. Unfortunately subsequent launches produce the same results.
Launching Premiere is just as big an issue. I've attached a screenshot of that.
I repaired disk permissions, but that didn't have any effect. I just pulled a Console log file that indicates, at least at the first part of the AE launch that the dynamic link manager is crashing repeatedly. Kicks out a new crash log every few seconds.
I pushed the crash log (converted to a text file) here, fwiw - dynamiclinkmanager_2015-06-20-120129-crash
Continuing my self diagnostics...
I created a new Admin user on my machine and was able to successfully launch AE with no issues.
So this tells me that my primary account has some "ghosts" that are mucking up the works. The problem is I'm nowhere closer to figure out what that could be, and it's not easy to remove things to find out. Most of the apps I thought would be an issue actually are installed for all users, and loaded up on my new test account, and worked fine.
I don't expect anyone to have clairvoyance into my machine's setup, but I'm hoping that someone else out there might be running into the same hiccup.