I am running on Win7 64bit.
I am also having this issue and it started with the update prior to dec 9th of technic launcher. I have some further insight possibly. The launcher runs perfect the First time and as long as I keep the launcher up it will continue to work great the first time (I can play any mod). Once I close the launcher, the next time I press "Play", I get the above error Every time. I have tried the steps Creeper has tried as well.
If I destroy the .technic directory and let everything download again I can play again, but I lose all my personal games/settings obviously. I made sure the java.exe and javaw.exe (which is what runs when you click technic launcher) are running as administrator, still have the issue.