Do you see that Razor colorization, intellisense has stopped working after you have installed Visual Studio Sp1 RTM? The reason is that you might have MVC3 RC installed on the box which is not compatible with Visual Studio 2010 Sp1 RTM. To fix, you would need to install MVC3 RTM. Following are the details of the issue.

What’s the issue?

Razor intellisense/colorization stops working after installing Visual Studio 2010 RTM

You might have MVC 3 RC with VS 2010 RTM that’s causing it.

How do I check which version of MVC3 do I have?

Simple way to check is to verify that the version of ProgramFilesMicrosoft ASP.NETASP.NET MVC 3AssembliesSystem.Web.Mvc.dll is 3.0.20105.0
If it’s not then most likely you have an older MVC3 build installed.

How to fix it?

1. Uninstall MVC 3 RC:
Follow Drew Miller’s post here http://drew-prog.blogspot.com/2010/11/how-to-uninstall-microsoft-aspnet-mvc-3.html on how to uninstall MVC 3 RC.

2. Install MVC 3 RTM either using WebPI or as a stand alone download.

Hope this helps.