jEdit is a free, multi-platform and my favorite text editor intended for programmers. Some time ago I encountered a problem with it, which repeated again today. So in case you also use this editor or found this post by searching Google, here is the solution:
Problem: jEdit (on Windows) doesn't start. Process is created and exists in memory, but it does nothing and shows no windows, so the only thing you can do is terminating it.
Solution: Terminate the jEdit process and the process of Java virtual machine, then browse to your user directory (like "C:\Users\Adam Sawicki" on my Windows 7) and delete the following small file in a sudirectory: ".jedit\server". After that you will be able to successfully start jEdit.