Got bit by the .NET 4 client again this week. Had a client ask me about installing the Pre-Call Diagnostic tool on a x64 platform as they couldn’t After trying to install on my box I kept getting an error about the UCMA Redistributal needing to be installed. I tried installing this manually and it would just bomb out.

Long story short, uninstalled and bam, the Pre-Call Diag tool installed just fine.