it could be that your paralell port is not configured properly in the bios, try other settings like ecp epp bi-directional etc.
also try using a battery that is not quite as new.
i had this problem with my laptop, and couldnt get it to work at all, i had to use a different machine.
try removing your lpt port from the device manager and let windows reinstall it after a reboot.
the easiest way to fix it would be to try another pc though.
also once you get into winlpc try erasing the chip first, before flashing, sometimes it glitches in the middle on the first try if you dont erase the chip.