A new version of .NET Framework Setup Verification tool, with preliminary support for Windows 8 and the .NET Framework 4.5 is now available for download.
"To use it, just launch netfx_setupverifier.exe and choose the .NET version you'd like to verify from the list (which is also a convenient way to see which .NET editions are installed on the current system)," explains Mike Williams.
Click "Verify Now" and "the program then checks for the presence of key files and directories, Registry keys and values for the .NET Framework, as well as running a tiny test application to confirm that everything is working correctly, before displaying its final verdict," Williams adds.
If the verification succeeds, it means there's nothing fundamentally wrong with the .NET Framework itself. But if you're not so lucky and verification fails, then clicking View Log to know more about any errors the Verification Tool might have found.
If the log doesn't provide anything particularly useful, check out this post that help you solve various .NET problems.
Start at "What to do if other .NET Framework setup troubleshooting steps do not help" for a good overview of your options.
You can download updated .NET Framework Setup Verification tool here.