kdbg does not work in first stage setup (qemu/Vbox)

during Setup, (using Qemu 0.13 and Vbox4) pressing the TAB-K (for "cont" or "set condition * first always" options)
system hangs (or keyboard is not responding)
the debug log still remain on:

Entered debugger on embedded INT3 at 0x0008:0x808fd1d6.
kdb:>

no way to restart or continue installation from this point.