As far as I can tell, it's a different variation of this:
Opening the .exe does nothing, or flashes a loading icon, or says "checking launcher version" then closes.
This is a Java issue. The most common cause is using 32 bit Java. If your Operating system is 64 bit, make sure you update to the latest 64 bit version of Java. Links on www.technicpack.net.
If no matter what you do, the exe just doens't work, go to your .techniclauncher folder and there should be a .jar in there. If not then download
it from www.technicpack.net and use that. Read further up the list for how to determine the bit version of your OS or JAVA.
Mixed with (I think) a little of this:
I've tried everything but I still can't get it to work with my 32 bit OS.
Not sure what to tell you. A temporary fix could be to use the .jar instead of the .exe which seems to work
for most people. If we manage to isolate a common cause to 32 bit OS issues then we'll update with a real fix.
I believe that the problem is being caused by some unknown link between the users encountering the problem. But it's been very difficult to try to establish what exactly is shared between people with this problem. Many people get very hostile when we tell them they are either a. breaking the rules or b. haven't provided enough information.
The .jar downloading as a .zip seems to be an IE issue.
It could be that people are downloading an incorrect version of Java, or downloading a bad file.
I'm hesitant to believe that the problem is because of the actual launcher or the website. I recently needed to have a clean start to fix an issue logging into my server, and I haven't had this issue.