You must use the role management tool to install or configure

I had that error when I tried to install .net framework 3.5 to install office server 2007 with SP1
To fix it is very easy:
1. Click the Start button
2. Right-Click on Computer and select Manage
3. In Server Manager click on Features
4. In features, click on Add features

5. Add the .NET Framework 3 or 3.5 features
And there you go, problem fixed :)