I have a TeamCity install on x32 Server2008 windows machine. I\'ve run the .net 4.5 web install. I\'ve also copied over the files from my x64 machine based on this article
I had the same problem and at the end it turned out that my defined build step to run MSBuild was configured wrong.
In my MSBuild build step the setting "MSBuild ToolsVersion" was set to 12.0 (default), which lead to the error "Unmet requirements: MSBuildTools12.0_x86_Path exists" on my system. Because I don't need the new MSBuild 12.0 to run my build, I changed this setting to 4.0 in my build step. This MSBuild version is correctly installed on my system. This solved the issue for me.