I think regenerator only works on internal drives (aka last time I used it, it was internal only via boot disk as I recall - been a while)
If I were you though I'd get a secondary system (something old ish) or remove your good drives from your PC when you try this stuff and plug the drive in internally
1) Because you don't know if the USB circuit is having a problem (or your drivers for such (unless your bios recognises USB to boot from)
2) The drive may have a power problem and well you want to minimise any loss here.