I came across this site, which drops this bomb:

February 29, 2012: updated for Qemu-1.0.1 – Still a “to be tested” version. See bug report win32: git rev 59f971d crashes when accessing disk (coroutine issue). In my version a workaround was to compile coroutine-win32.c without optimisation (-O0): contains qemu-system-arm.exe, qemu-system-i386.exe, qemu-system-ppc.exe, qemu-system-sparc.exe, qemu-system-x86_64.exe and the linux-0.2.img image

Well isn’t that amazing… I know I’d given up on it as as soon as some OS’s accessed the hard disk once they’ve initialized in protected mode it’d just lock up…

I may well have to revisit my Win32 builds of Qemu 1.0.1