USB Blaster shown as "Unknown Device"

Thanks for the replies guys.

1. I did uninstall the device from Device Manager and rebooted machine but problem still exist.

2. I also tried deleting the files usbblstr32.dll, usbblstrlang.dll and usbblstrui.dll in the c:\windows\system32 folder. Same result.

3. Also tried installing or updating the driver for the Unknown Device via the driver at the folder C:\altera\91\quartus\drivers\usb-blaster. Add Hardware Wizard would say it can't find a suitable driver for it.

4. Problem is happening to like 60+ out of 100 machines.

5. I am now re-imaging some machines to see if I can regenerate the problem. Although don't really know how it happened.

6. I also noted that while in Device Manager I checked the driver detail of the Unknown Device and Windows said no drive files are available.

I am now wonder if perhaps Windows no longer see the USB Balster or DE2/0 board as such, so it will just install it as an unknown device.

In normal situation, a USB Blaster will appear as "Altera USB Blaster".