I can confirm the crash with the latest nightly (rev10320). It doesn't occur on my custom x64 build (rev10305).
What compiler version is used with your custom x64 build?
I am starting to think it might be a Compiler and/or wxWidgets bug.
I have failed to see the problem using TDM MinGW GCC 4.7.1 under Windows 7 64 bit Home Pro.
But, I do see it under MinGW GCC 4.9.?2? under Windows 7 32 bit Ultimate.
Tim S.