A few ideas to toy with;
1)If present uninstall the NVIDIA IDE drivers or Intel Application Accelerator.
2)Remove the 1640 from the device manager and let windows re-detect and install it.
3)Try flashing the drive in Windows safe mode.
4)If there was a BSHB.cvt you could use WinDWFlash to flash the firmware however I'm not sure if BSHB is available in .cvt form, I only know of BSGB.cvt at the moment.
5)Try re-flashing BSGB does the same thing happen as with BSHB ?
6)Plug the drive into another computer and see if you can flash it from their
7)Remove anything else on the power cable the 1640 is plugged into and try flashing it again.