It's strange how the recent version works for some people but not for others. I've noticed this has been the case for a no. of versions that have been released.
The suggestions I can make are (reiterating a little):

1. (a) Make sure you have the most recent version of Java. (b) Try the Standalone Java installer because installing over the net can cause side fx.

2. Do a (a) Safe Mode start & (b) Repair Permissions, & then check with (c) Disk Utility & fsck, & if necessary run all other mac & 3rd party utilities (eg: DiskWarrior, Norton Utilities & AV, TechTool Pro) on your computer.

3. Uninstall LW completely (do a complete search to make sure you have trashed every single LW item incl. prefs. - though you could move the incomplete files including download.dat & bak somewhere else temporarily.) Then reinstall.

4. Try out the LW Beta version (Pro users will find download link at bottom of their personal dwnld page)

5. Install in a new admin user account to isolate a home account problem

6. Go back to earlier version of LW until a new update comes out.

7. (a) Be radical & start completely over by reinstalling OSX & updates & then LW (as last resort only.) (b) Else, & probably 'preferable' is to install the Apple Combo Standalone installer. Updating over the net can sometimes cause issues so using a standalone installer & in one installation hit such as the combo seems to overcome some of those issues.

8. Try the Jum Build which is a beta (more experimental than the regular LW beta) but easier to install.

All these suggestions have worked! But they don't all work for everybody. One of them should/will!