First check here:
http://forums.technicpack.net/threads/common-problems-and-solutions.10851/
Troubleshoot:
Make sure your anti-virus and firewalls are disabled while trying to connect to minecraft.net (while logging in, connecting to a server)
Uninstall Java, then delete your .techniclauncher folder. Restart your computer (it's not required, but it never hurts to give it a break)
Reinstall the correct version of Java for your computer (ensure the bit type matches)
Redownload the Launcher.
Try to run the .exe, if this does not work, look in your .techniclauncher folder, make sure you have a .jar file in there.
If you do not, and the .exe doesn't work, do this:
I am getting a “Technic Launcher has Stopped Working Error”!
If your launcher is encountering this error, a solution is to download the .jar file from http://www.technicpack.net/download/ (pick the third from the left (Linux/Jar)). If you are using Internet Explorer you will also need to change the file extension (the ending of the file) to .jar instead of .zip. Once you’ve done that, all you need to do is double-click on the file to run the launcher.
If double click doesn't work with the .jar:
Right click on the .jar file, open with Java.
If none of those work, try running as administrator.