The short version of this answer is that you're installing an old version of Holiday Lights. You can either:

• Use the latest setup program from our Download Center, which avoids this message

• Ignore the message and continue; Holiday Lights will work with no trouble

 
The Long Answer

It's important to note that this message isn't saying that Holiday Lights is the wrong version. Rather, it's referring to a file named CTL3D32.DLL that's already on your computer, warning you that the file of that name on your disk isn't the normal one that comes with your version of Windows.

Another program you previously installed has mistakenly replaced that file with one designed for Windows NT. Because of this, that file can't be used. The installer for Holiday Lights 4.0.2 and earlier tries to use that file, but the file displays the error message you see.

(We agree that the warning message could be much better worded, but unfortunately the message is actually coming from the CTL3D32 file itself, and was put there by Microsoft — we can't control what it says.)

This problem doesn't mean you can't install Holiday Lights, though; simply go ahead and continue the installation — it will work with no trouble. Holiday Lights will simply ignore the incorrect file, and you won't see the message again.

There is a Web page devoted to the problem that explains why it happens, and how to fix it permanently so it won't happen with other programs.

 
See also:
How do I know what version I'm using?
How do I upgrade if I'm using a previous version?