So the obvious thing to do would be to put Mark's compiled kernels back onto the player and see if the problem goes away...

It did not Which is what I expected, because I did not make any significant changes in my build.
What may be important - I am using v3 alpha player software. Could this be a problem? I understand that additional options are built into hijack kernel, but maybe the kernel uses some code (which could change) from the player software?