Quartus 14.1 pollutes 13.0 project

I'm running the Linux version of Quartus, so I can't give you the exact path, or instructions, but if you go to your device manager, you should be able to find the USB blaster under USB devices, then modify the driver by pointing it to the one in the quartus 13.0 installation directory.

I think it's in the ../13.0/quartus/drivers directory. But again it's been awhile.

For Windows 7.0 just right click on "Computer" and select "Properties", "Device Manager".

Then under USB devices, expand it and find the USB Blaster, Right Click on it, select "Properties" and hit the "Drivers" Tab, then click on "Update Driver" and follow the prompts. Make sure you direct it to the 13.0 installation driver directory.

For Windows 8.x you need to search for "Device Manager" But I avoid 8.x, so your are more on your own there..

Pete