It's certainly possible that I'm not understanding correctly how this works, but I thought SFC /scannow checked the contents of the DLL cache against the distribution media, and the thing I am trying to figure out is how to tell it correctly where to find the distribution media. Originally, it wanted to look at D:\ or D:\i386 if the distribution media was a CD in the D: drive. I copied those directories to C:\Setup\... and I've been trying to tell SFC to look there instead. It works fine when I only had the original CD, but I got messed up when I added the SP3 CD's i386 directory also.