Modpacks not launching

[orangeflower50]

I play on a Mac computer. Every time I try to start up a modpack, it goes to a black screen then quits, sending me back to the Launcher. How do I solve this problem? Modpacks used to work perfectly fine.

All of the "official" packs work perfectly fine. All other modpacks are experiencing the issues. Can anyone help? Thanks in advance.

[Munaus]

post the log

logs can be found when clicking the Cog-Wheel button on the top right corner on the launcher window.
If you can't open the launcher the logs can also be found inside "User Name" -> Library -> Application Support -> techniclauncher -> logs

Paste the content on pastebin.com or paste.ubuntu.com and give the link.

Edited June 15, 2015 by Munaus
corrected pathway