It seems that your ASP.NET version is not properly installed.
Follow these steps, to re-install it
Open a command prompt and navigate to this dir
C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727
Run these commands in this order from command prompt:
aspnet_regiis.exe –i
aspnet_regiis.exe –e
IISReset (To restart the IIS)
You may also need to restart the computer