Please try the instructions below to fully clean Alcohol and SPTD from your system and try to install it again:
To uninstall Alcohol you should use the Uninstall icon on Alcohol program group in the Start menu. For the case you have deleted Alcohol Uninstall icon from Start menu you should just browse to Alcohol folder and manually run "uninst.exe".
If you are unable to uninstall Alcohol using the uninstaller (this means installation is corrupted) then please just delete all files from Alcohol folder (default: "C:\Program Files\Alcohol Soft\Alcohol 120" or "C:\Program Files (x86)\Alcohol Soft\Alcohol 120" on 64-bit systems), then download and run the following tool to completely remove SPTD driver installed by Alcohol:
After removing SPTD from your system and restarting Windows as requested by the tool (please note that you may need to reboot twice in some cases, the tool will tell you) then please try to reinstall the latest version of Alcohol again.
Alternatively to the sptdremov tool you may remove SPTD manually, to do it please run regedit.exe, then browse to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ and delete sptd and sptd2 key (you may need to adjust cfg key permissions to delete it). Also please browse to c:\WINDOWS\system32\drivers and delete sptd.sys and sptd2.sys file(s). Restart Windows. If you were unable to delete SPTD key in registry then please try to delete it again now, after deleting the driver file(s) and restarting Windows, or just try to remove it in Windows safe-mode, it is very important you delete this key.
If you continue having problems please try to temporarily disable (or even uninstall) your real-time antivirus, firewall or any other security software and try to install Alcohol again. We had some reports recently of anti-virus and security software (like ZoneAlarm, Spyware Doctor, F-Secure and PC Tools ThreadFire products) preventing SPTD to install and/or work correctly.