Arduino IDE 1.6.4 wont run , Windows 8.1pro 64bit

If anyone can help. I just Upgraded from 1.6.3 to 1.6.4 and now the IDE starts and then dies. Running Windows 8.1pro 64bit, Java 8 update 45.
The output from arduino_debug is as follows:

"C:\Program Files (x86)\Arduino\arduino_debug.exe
Loading configuration…
Initializing packages…
jave.lang.NullPointerExecption
at cc.arduino.contributions.packages.ContributedToolReference.resolve(ContributedToolReference.java:43)
at cc.arduino.contributions.packages.ContributedPlatform.resolveToolsDependencies(ContributedPlatform.java:76)
at cc.arduino.contributions.packages.ContributionsIndexer.parseIndex(ContributionsIndexer.java:92)
at processing.app.BaseNoGui.initPackages(BaseNoGui.java:600)
at processing.app.Base.(Base.java:271)
at processing.app.Base.guardedMain(Base.java:215)
at processing.app.Base.main(Base.java:128) "

IDE 1.6.3 works fine, would like to be-able to upgrade to the new IDE.

Thanks
Ernie

Try installing the hourly build. Federico Fissore has just made a fix to the Arduino IDE that may solve your problem.

Downgrade to 1.6.3 imo unless you want to be a guinea pig.

The 1.6.x versions have been really spotty - and they turn on the upgrade nag screen when a new version is released, even if it's a total lemon.

1.6.3 works well, but I like that 1.6.4 added Compiler Warnings levels selected via File > Preferences. That said, 1.6.4 has not been good to me. There have been some major improvements since and I think 1.6.5 is going to be the best IDE yet by far. I've been using the hourly builds lately and am really happy with them.

The error messages posted by the OP makes me think they are using Boards Manager to install 3rd party Boards and that is only available in 1.6.4+