[flexcoders] Flex Builder 3 beta 3 - Drag and Drop no longer works

[Andrew Jones]

Hello - 
I have 2 flex projects (built in Flex Builder 3 beta 2) that both use
a lot of drag/drop in the application.  This morning I upgraded to
Flex Builder 3 beta 3, and now I get an error everytime I click on an
object to initiate a drag.  The error in the console is as follows:
undefined
        at
mx.collections::ArrayList()[E:\dev\flex_3_beta3\sdk\frameworks\projects\framework\src\mx\collections\ArrayList.as:81]
        at mx.collections::ArrayCollection/set
source()[E:\dev\flex_3_beta3\sdk\frameworks\projects\framework\src\mx\collections\ArrayCollection.as:114]
        at
mx.collections::ArrayCollection()[E:\dev\flex_3_beta3\sdk\frameworks\projects\framework\src\mx\collections\ArrayCollection.as:78]
        at comp::Activity()[/Users/andrewjones/Documents/Flex Builder
3/ParkCity/flex_src/comp/Activity.mxml:163]

And it opens the ArrayList.as class file in debug mode.

Has anyone else run into this problem, and if so can you let me know
what I need to change to make drag/drop work in F3 beta 3?

Thanks!