I know this has been addressed many times before but nothing seems to work. I have had a JTAGICE MKII connected to a Butterfly and have been successfully programming and debugging with Studio 4.17. Fired it up this morning and I get the dreaded "Failed to identify target" message. Nothing has been changed since it last worked (not knowingly at least).
After selecting the "Connect to the selected AVR programmer" icon the Main tab shows the correct MCU (Atmega169) and Programming Mode and Target Setting is set to JTAG. The HW Settings tab shows VTarget = 3.9v (external supply) or 2.9v (battery).
Attempts to erase the device, read signature and starting debugging all say "Failed to identify target".