Hello everyone,
First off, thank you for taking the time to answer my question.
I have had the same problem since a couple of versions where everytime i am on the techic launcher, every mods work fine except for the tekkit one. when i press "Play" the game takes ages to load, or does not load at all. Once loaded, if i create a new world the game crashes and sends me back to the launcher, and when i play a game, after about 5-10 minutes it crashes in the same way.
Please if someone had the same problem and figured it out, tell me... I have been dreading to play the tekkit again since ages.