Hi

Shutdown, wait a couple of minutes, restart and try again.

Then if LW won't install, more info will help.

To get more details on the error message, open Console in your Applications/Utilities folder. A window will open that gives info about what is going on.

Try double-clicking the installer on the .dmg again. An error message will probably show in the Console window

btw--I've seen something like that on brand new machines, or the first time java is started on some new OS X installs.