So I tried to install VS2008 b2 on my work laptop this morning and got a shower of red fail icons while .NET 3.5 while being installed. All the log files for this install are in the %temp% directory, so i had a look there. And in the log dd_dotnetfx35error.txt, the less than useful line:
Microsoft .NET Framework 3.0a: [2] Error: Installation failed for component Microsoft .NET Framework 3.0a. MSI returned error code 1603
1603 is just the code for a fatal error, so that's not much use. The problem is with the .NET 3.0 install, so I had a look in dd_NET_Framework30_Setup6CEB.txt. Sure...