The only reason where you absolutely have to flash Toppy firmware via the USB port is when the Toppy is very sick and you can't use HD2FW.
If you are forced to use the failsafe mechanism then it is a prerequisite that your PC can recognise the Toppy Boot loader device & has drivers for it.
The symptoms of this not working properly are that the Toppy reboots normally instead of rebooting into the firmware update mode, even though the firmware updater is waiting on the PC to detect the Toppy boot sequence.
If Wuppy has been installed you may need to uninstall Wuppy & remove the drivers manually before the Toppy drivers for the USB loader can be installed properly.
The driver in question is TfBulk.SYS To prevent the driver associated with Wuppy being reinstalled again when you rediscover the Toppy TfBulk.inf also need to be removed, including any cached copies, the names of which can often be discovered by looking at \Windows\setupapi.log after the USB driver discovery process has been run.
Ask more questions if you are not confident to do this & also remember to delete the USB device from device manager first (you may need to select "view" / "show hidden devices")
This is written with Window XP in mind, not Vista.
Another option is to find an alternative PC to flash empty settings. (or try the serial method).