Cause: For security reasons some machines are built with no C:\ drive and KEYLOK Installer by default looks for C:\ drive to install the driver, causing the error you're experiencing.
Solution: To install on a machine with no C:\ drive. Copy the USBKey.sys or USBKey64.sys and USBKey.inf or USBKey64.inf, located on KEYLOK CD “Send to End-Users\Optional Manual Installation Files”, to DriveLetter\Windows\System32. Edit the USBKey.inf or USBKey64.inf so the bottom line reads DISKID1= “Hard Driver YOUR DRIVE LETTER” instead of “DiskID1 = HARD Drive C:” and save the file. Go to the Device Manager, plug in the Key and when it appears in Device Manager Right-Click and select Update Driver and Select Install from specific location then navigate to System 32 and click on Install Driver. This should resolve the issue.