When using the debug kernel I'm getting a DSI while closing the Tasks window.
Thomas gave me the following explaination:
The 0xcccccccc reference is a typical indication of accessing the pred/succ pointers of a list node after remove.
The debug kernels clear the succ and pred pointers with 0xcccccccc to make people aware of this problem.
The regular kernel doesn't expose the bug so you have to use the debug one to reproduce.
See crashlog for more details.
BTW, that's with Scout 37.290 [OS4/PPC] (23.4.2006)