I have been following this problem for some time now and have tried to fix it using some of the suggestions listed. NO LUCK !!
The problem for me is, I am not a computer guy. all I want to do is run my arduino IDE and play with some code. most of the fix's are beyond my computing skills.
This seems like a problem with the Arduino IDE code. so what are the people back at Arduino doing about it?
I have the Arduino IDE installed on two computers and they both have crashed. same problem "Launch4j error" what am I supposed to do? just throw away months of work and forget about it.
To me this is serious. please Arduino people, get with the program! "Pun intended" put this thing to rest once and for all.