Bus error - What does it mean?

[setera]

I'm working on an application using GCC and POSE.  I'm using
SysCreateDataBaseList to create a list of application databases and then later
trying to lock the returned handle in the List Draw Callback Function that I've
defined.  I keep getting a bus error when attempting to lock the handle.  What
the heck does this mean and why is it happening?  The handle is not null and
appears to be the same value as it was immediately following the call to
SysCreateDataBaseList.

Thanks,
Craig