Problem installing .NET Framework 3.5 SP1

When I install the SP1 update. NET Framework 3.5, everything is good, but download to install, there is a blockage and the program quits.

Anything that is to say is: [01/28/09, 22:24:59] Microsoft. NET Framework 3.0 SP2 x86: [2] Error: Installation failed for component Microsoft. NET Framework 3.0 SP2 x86. MSI returned error code 1603
[01/28/09, 22:24:59] Microsoft. NET Framework 3.0 SP2 x86: [2] Error: Installation failed for component Microsoft. NET Framework 3.0 SP2 x86. MSI returned error code 1603
[01/30/09, 18:55:02] Microsoft. NET Framework 3.0 SP2 x86: [2] Error: Installation failed for component Microsoft. NET Framework 3.0 SP2 x86. MSI returned error code 1603

And so on...

EDIT: I said that I have all the old versions. NET Framework. Should I uninstall it?

See suggestions given in similar type of threads: http://forums.techarena.in/windows-update/1066811.htm
http://forums.techarena.in/windows-update/1112411.htm
http://forums.techarena.in/vista-set...all/810019.htm
http://forums.techarena.in/windows-update/944656.htm

Resolution:
Cause determined after comparing various logs that the Cryptographic Services runs under “Network Service” which would require Users to have read access. Provided BUILTIN\Users with read access permission to Drive C and the .Net Framework 3.5 SP 1 installed successfully

Important Note: This may vary in some machines and the error message may be also different, in that case feel free to contact me or E Mail me. As .Net Framework 3.5 SP1 is a new release and people facing the similar kind of issue will help them resolving the installation issue.

I also experienced it on my XP.

I searched for it, and the result was that some kind of beta .NET remained on my PC.

There is a tool to remove all .NET framework from the system. I run it and after it I successfully installed 3.5 SP1.