Try reinstalling Processing, the files might have gotten corrupted.

My suggestion: remove the Java install you have currently and update to a newer JDK version. You can find it here: http://www.oracle.com/technetwork/java/javase/downloads/index.html

I had some issue with Win7 and an older Java version. Removing and updating solved the problem for me.

Cheers

You don't tell what version of Processing you have installed. And if that's 2.0, did you chose the 32bit or the 64bit version?

The Windows version of Processing 2.0 now comes with Java bundled (there is no longer a no-Java version ), so there should be no problem with the version installed on the system.

I downloaded the 2.0 Beta 3 (10 September 2012)
and i have 64 bit windows. I have the most recent java sdk installed. 

And how do you try to run it? Just double-click on Processing.exe?
Have you tried to download the package again? Or perhaps a previous beta?

and how would i download a previous version?

They are listed in the Download page...