These panics are raised in debug builds, and are caused when the heap debugging functions detect a memory leak.
nnnnnnnn
This panic is raised by the RHeap::DbgMarkEnd() and User::DbgMarkEnd() when the number of heap cells at the current nested level is not as expected.
RHeap::DbgMarkEnd()
User::DbgMarkEnd()
nnnnnnnn is the hexadecimal pointer to the first orphaned heap cell.