Through my automated crash collection for MaxTo I got the following crash report:
V8.12.0.0 - System.ComponentModel.Win32Exception - :Void UpdateLayered():0
The problem probably dones't lie in your WndProc - the reason you see it in your call stacks is because pretty much everything GUI-related on Windows go through the WIN32 window procedure. Overriding it in your control simply gives you a hook point to process low-level stuff before higher-level .NET framework processing is done.
This is going to be a complete shot in the dark, but perhaps this post could be relevant? - probably not with those stack traces, though.