You're in the wrong section. Technic or Tekkit, and what version?
Things to try:
1) Install OptiFine Standard instead of the one that comes with the pack. There are sometimes issues with Smooth or whichever one it is.
2) Remove all copies of Java 6 and install 64-bit 7u5. I'd do this anyway, even if it doesn't solve the problem.
3) If that's the entire log file, I'd be very surprised, but if it is, post launcher_1.log too. If it isn't, stick the whole thing in pastebin and post that.