The Flash cache on your computer is corrupted. You have to clear it. There are a few ways.
One way is some URL on the flash website (well macromedia), you have to seek out the servers that your computer uses for Bushwhacker and zero that out. http://www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager07.html

An easier way is while BW is loading, right click and select settings for flash. Go to the tab that has drive storage and unclick the button if set and move the slider to 0.

A third way is to use a program like cccleaner.

In all cases, after you do that you have to reload bushwhacker. It will ask you about storing on the hard drive and flash will ask for permission to do so. Say yes to both. And then twiddle your thumbs for 5 to 10 minutes as it takes to completely reload this huge game.

I do this once a week. And I do this just prior to and Holiday Events or Updates no matter when my 'weekly' clearing happened.