Unable to find c:\windows\system32\mfc100d.dll

I have a very strange problem.

I am trying to run a console application that I build using VS2010 and get the error mfc100d.dll not found. However this dll is present in c:\windows\system32 and my path is c:\windows\system32

If I copy the file from c:\windows\system32 to my current directory it works.

If I add C:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\redist\Debug_NonRedist\x86\Microsoft.VC100.DebugMFC\ to my path, it also works.

It was all working fine until I uninstalled a program yesterday and installed new version of it. But the thing I just can't understand is why I am getting errors when the mfc100d.dll is really there in the C:\windows\system32 path.

And, yes, I do have the rights to read the file, how else can I copy it...