Nope I'm saying in order to diagnose an issue and blame something you need to come up with something technical rather than point to something and blame it, it could easily be something else and there could easily be another solution.
To say that every-time they install .NET 4 it screws their machine up clearly points to another issue in my experience, far away from .NET
The last poster said he doesn't want to connect to the internet anymore... fair enough. Somebody else however might say I BLAME THE INTERNET! And then attempt to back it up by stating "thousand have used the internet and it crashed their machines". So you see what I mean, you need to be specific before you do the finger pointing. Look in logs, attempt repairs, check your hard drive. Most non-experts should be able to handle it to be honest if they take time to google, so I apologize for sounding a little snobbish.
For instance maybe it could be firewall type software was blocking the .NET application communication with another app. The fact that Sonar does NOT run on .NET here also seems a little strange. Why are you installing in the first place? Well because there's something else running on it that you are not tell us about. That could be something that's interfacing with your drivers... etc etc.
There's a bigger picture at work here.