SQL Server - .Net Framework no se activa.

Tengo un Servidor Dell PowerEdge T410. Quiero instalarle SQL Server 2008 Standard Edition for Small Business. Al tratar de instalarlo me dice que tengo que ir al Server Manager y activar .Net Framework 3.5 SP 1. Ya lo hice varias veces pero cuando llega aproximadamente al 75%, el Servidor se pasma y ya no continúa aunque lo deje 2 días prendido; cuando esto pasa tengo que apagarlo quitándole la energía eléctrica porque está completamente trabado. ¿Cómo puedo solucionar este problema?

09/06/2010 14:43:43.847 ======================================================================
09/06/2010 14:43:43.879 Setup launched
09/06/2010 14:43:43.910 Attempting to determine media source
09/06/2010 14:43:43.941 Media source value not specified on command line argument.
09/06/2010 14:43:43.957 Setup is launched from media directly so default the value to the current folder.
09/06/2010 14:43:43.988 Media source: F:\
09/06/2010 14:43:44.019 Attempt to determine media layout based on file 'F:\mediainfo.xml'.
09/06/2010 14:43:44.409 Media layout is detected as: Full
09/06/2010 14:43:44.440 Media LCID is detected as: 3082
09/06/2010 14:43:44.471 Local setup.exe not found, so continuing to run setup.exe from media.
09/06/2010 14:43:44.518 /? or /HELP or /ACTION=HELP specified: false
09/06/2010 14:43:44.534 Help display: false
09/06/2010 14:43:44.565 Checking to see if we need to install .Net version 3.5
09/06/2010 14:43:44.596 Determining the cluster status of the local machine.
09/06/2010 14:43:44.659 The local machine is not configured as a cluster node.
09/06/2010 14:43:44.690 Attempting to find media for .Net version 3.5
09/06/2010 14:43:45.220 .Net version 3.5 needs to be installed from media: F:\
09/06/2010 14:43:45.283 Attempting to install .Net version 3.5
09/06/2010 14:48:17.534 Received exit code 5100 from installing .Net version 3.5
09/06/2010 14:48:28.205 .Net version 3.5 installation failed, so setup will close. Error code: 5100
09/06/2010 14:48:28.220 Setup closed with exit code: 0x84C40013
09/06/2010 14:48:28.251 ======================================================================