A fresh installation of CotN refuses to start on my PC, complaining that this DLL is missing. I assume that this is because I've recently replaced my system drive, and have a new Win7 installation that went straight to DirectX 11, and so doesn't have the DirectX 9 DLLs available?

I don't know much about DirectX, and Microsoft's Windows Support site doesn't seem very helpful on this issue.

Should I just download and install DirectX 9? Will that mess up my DirectX 11?

Or do I just need to download the missing DLL and put it in my SysWOW64 folder? I've found a few sites with downloads available, but they look a bit dodgy, and so I'm wary.

Any advice very gratefully received! ;-)

It's OK, I've sorted it out. ;-)

It is a DirectX issue, as I supposed. For anyne else who comes across a similar problem, I'll briefly document the solution:

There's a Web Installer module for Direct X available from the Microsoft Support website, but it doesn't fix the problem. It appears to be more a repair utility dsigned for a damaged DirectX installation, or to address DirectX incompatibility in the system. It appears to rely on backwards compatibility within DirectX !!1 to address software that needs DirectX 9 compatibility, and so doesn't physically install the older DLLs. But CotN is written to look for d3dx9_33.dll by name, so the Web Installer for DirectX doesn't fix the problem.

However, I did find the DirectX Runtime Redistributable for download at http://www.microsoft.com/en-us/download/details.aspx?id=8109; I downloaded that, created a restore point, took a deep breath, and installed the older DirectX files, errm, directly.. And it worked.

After a system boot, CotN is working fine. Huzzah!!