[Copytrooper]

Open registry editor (run regedit) and check if one the following key exists:
HKEY_LOCAL_MACHINE\Software\19659239224e364682fa4b af72c53ea4 (DT Light),
HKEY_LOCAL_MACHINE\Software\14919ea49a8f3b4aa3cf10 58d9a64cec (DT Pro).
This is volatile key of Daemon Tools installation which should disappear after reboot. If it still exists, delete it, and try again.

If you've problems with SPTD layer installation download SPTD stand-alone installer:
http://www.disc-tools.com/download/sptd
x86 version is for 32bit OS (Windows 2000, XP and above),
x64 version is for 64bit OS (Windows XP x64, Vista 64bit, etc.)

Run the SPTD installer and update to latest version. After reboot run installer again, and check the message. If it says SPTD version (currently v1.60) detected, SPTD installed correctly. You can continue with Daemon Tools installation then.
If it says no SPTD layer version detected, or gives an error message, DO NOT install Daemon Tools! Search the forum first for a thread covering your problem, before starting a new one!

Also check if r0 key exists in
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\sptd.
Delete r0, reboot, then try again.

As last resort un-install all software using SPTD layer (e.g. Daemon Tools, Alcohol), open registry editor, browse to the following key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Servic es\sptd
and set Start value to 4 (i.e. disabled), and reboot.
After reboot delete complete sptd key in services hive - you must enable all permissions on sptd/cfg key first.
Then reboot, and re-install, beginning with SPTD layer. After reboot check correct SPTD layer installation (see above) before re-installation of Daemon Tools!