USB Blaster disappears

Tried 10.1sp1 driver download. Doesn't help.

I can run Quartus II Programmer from Nios EDS and download a sof. Sometimes I can do it a second time. It will hang sometime during the download by the third time I try. If I disconnect the blaster and reconnect, Quartus comes back alive and says it failed.

nios2-flash-programmer _always_ fails at some point during checksumming, erasing, or programming. When it does, it hangs if running from the GUI, or if running from a command line it just fails one of the operations.

Once the failure occurs, the USB-Blaster is no longer listed in the Quartus programmer or flash programmer GUIs and from the command line, nios2-flash-programmer says there is no such device 'USB Blaster on local host'.

So GUIs hang, command line fails, then the blaster is gone from the list, although it is still there under Device Manager. I suspect the JTAG server has the device locked up and unavailable. If I unplug/replug the blaster, it is available again. This is different than I have reported before, I was mistaken.

This all worked just fine on my old machine running Windows XP with Quartus 10.1sp1. I've verified there is no appreciable noise on the JTAG, I have blown $$$ on a new Blaster, I have run from within virtual XP mode, I have nothing else to try.

Has anyone else used the flash programmer with a dual NIOS? Could there be some new conflict in the software on Windows 7 with a dual NIOS design?