Bad address when casting FWaitHandle object to TWaiter

[orthopteroid]

I'm not exactly sure whats going on here but it looks like the cast to TWaiter returned an invalid address into RAX, causing an address exception when trying to set .Signalled true.

app had a ram commit of 23GB, with working set of 21GB (machine has 32GB) with 14 running threads using the Parallel.ForEach<Integer>( ... ).NumTasks( System.CPUCount ).Execute( ...) api.