Missing .NET Assemblies

Hi All,

First post. Couldn't find a suitable sub-forum to post this question in, so I figured I'd start in General.

Anyway, I seem to missing some .NET assemblies. Specifically I can't find System.Diagnostics, and I can't find any information on the web about why I'm missing it or where to get it. I have a theory though:

I need to install (some distribution of) Visual Studio.

I hope I am wrong, as I don't want to install Visual Studio on this computer. I only need to interact with a tiny number of assemblies through PHP's DOTNET class, so installing VS seems like a lot of overkill.

Anybody out there who has any information on this? BTW, using the standard .NET 4 Framework.

No dice. I installed the full framework, but when I navigate to C:\Windows\assembly, its still not showing up.

I've checked my work computer as well and for some reason it doesn't exist there either. It also seems to invalidate my theory that I might need Visual Studio, as this workstation has the full version as well as other MS development applications like SQL Server Management Studio.

No luck at Microsoft Answers either. Nobody seems to know where System.Diagnostics comes from and why it doesn't exist on my machine. For all this, I can't shake the feeling that I'm missing something incredibly trivial, though.