i read alot of comments about ns pro 3.8.7, because i had same problems.
its about 99% sure the old drivers are conflicting. I tried everything about 3 times install and delete drivers.
Then i tried FTDI CLEAN, , its asking new drivers, so first install 3.8.7. then FTDI clean will delete all drivers and u instal drivers from programfiles\nspro\drivers. Now its working 100%
I unlock 24 pieces u700 and u700v verry easy. So Elco is best programmer;). Just install it read bellow
Download here FTDI CLEAN http://www.ftdichip.com/Resources/Utilities/FTClean.zip
so there are 6 steps
1.Uninstall older NsPro versions.
2.Delete NsPro folder from C:\Program Files
3.Install last NsPro version
4. Unplug all ftdi device from usb port, right clik my computer > properties > hardware > device manager
> view > show hidden device > Ports (COM&LPT) > UNINSTALL ALL HIDDEN PORTS.
5. To clean up your system from messed of ftdi device, you will need to run THIS PROGRAM
6. reboot. Plug your ftdi box one by one. You may reconfigure your box driver now.
I hope this work for all, and Elco pls add it to Sticky , it will help 100% this cleans all ftdi drivers
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