Ive read multiple forum threads about this issue, and neither of which i have found fixes my issue. I have alot of programs that require .Net framework 3.5.1sp and when they run they don't work. when i try to enable .NF3.5.1 it says it cannot connect to the windows update, and I've downloaded updates, and I'm clearly connected to the internet. can someone please help? It goes from Planning to change features > i click Connect to windows update > it doesn't work and says this Reason: 0x800f0906 - Windows could not download necessary files from Windows Update. Check your network connection, and try again by pressing the "Retry" button below Do i need to re-download Windows 8 Developer Preview X64 off the Microsoft website and use up another DVD?

I have the Consumer Preview and same error.

This worked :

If the user performs a clean installation of Windows Developer Preview, apps that require .NET Framework 3.5 (or 2.0) will trigger a request for the necessary files. Normally the missing files will be downloaded from Windows Update (after asking the user for permission), but if access to Windows Update is not possible, enabling .NET Framework 3.5 will fail.
Mitigation

To enable .NET Framework 3.5 on only a few machines with clean installs of Windows Developer Preview:
1.Copy\sources\sxs\ from the mounted operating system build ISO image to dotnet35 or similar folder. For example:
xcopy e:\sources\sxs\*.* c:\dotnet35 /s
2.Execute the following command line using admin privileges:
Dism.exe /online /enable-feature /featurename:NetFX3 /All /Source:c:\dotnet35 /LimitAccess